opening Python IDLE with AutoHotKey

opening Python IDLE with AutoHotKey - python

I've been messing around with AutoHotKey, trying to create some useful shortcuts for myself. I can open file explorer, calculator, chrome, etc., but I haven't been able to write a program that opens Python IDLE.
My program says:
!t::
Run pythonw
return
I've tried pythonw.exe, python.exe, python, python3.exe, and a bunch of other combinations. Any idea why it isn't working? Thanks!

So, your problem is that Python IDLE is different from pythonw.exe, python.exe, python, python3.exe .
Python IDLE is an IDE or Code Editor provided with python whereas pythonw.exe, python.exe, python, python3.exe are the python interpreter.
pythonw.exe - for executing python scripts without opening console window(Hidden)
python OR python3.exe OR python3.exe - are the same, that is the normal python interpreter.
So to open IDLE you should execute the IDLE file not the interpreter.
The path for IDLE(in Windows Computer) is usually :
C:\Python39\Lib\idlelib\idle.bat
Here the Python version is 3.9 but it may be different in your case!
Check for the version you installed by opening command prompt and typing :
C:\>python --version
Python 3.9.1

Turning the info that Jaysmito provided into an AutoHotkey Script:
!t::
Run C:\Python39\Lib\idlelib\idle.bat
return
However, the Python39 part of the directory above will vary based on which version of python you have installed. To check which version of Python you are using, use the python --version command in a command prompt window. Then if your version of Python is not in the 3.9.* range, change the directory above to match your version.
For example, if your version is in the 2.7.* range, your directory would be something like Run C:\Python27\Lib\idlelib\idle.bat, with the Python39 from above changed to Python27.

idle.bat is Windows specific, and there are Windows-specific reasons for its existence. The generic way to start IDLE in its default startup mode (partly user customizable) is somepython -m idlelib where somepython refers to and start a python binary. It can be python, pythonw (Windows), python3 (*nix), or py -3.y (Windows). For 2.x, use idlelib.idle instead of idlelib.

Related

How to set python 3.x priority? [duplicate]

I installed Python 2.6 and Python 3.1 on Windows 7 and set environment variable: path = d:\python2.6.
When I run python in cmd, it displays the python version 2.6, which is what I want!
But, when I wrote a script in a bat file and ran it, the displayed python version was 3.1.
import sys
print (sys.version)
What's going on here?

This is if you have both the versions installed.
Go to This PC → Right-click → Click on Properties → Advanced System Settings.
You will see the System Properties. From here navigate to the Advanced Tab -> Click on Environment Variables.
You will see a top half for the user variables and the bottom half for System variables.
Check the System Variables and double-click on the Path (to edit the Path).
Check for the path of Python(which you wish to run i.e. Python 2.x or 3.x) and move it to the top of the Path list.
Restart the Command Prompt, and now when you check the version of Python, it should correctly display the required version.

The Python installer installs Python Launcher for Windows. This program (py.exe) is associated with the Python file extensions and looks for a "shebang" comment to specify the python version to run. This allows many versions of Python to co-exist and allows Python scripts to explicitly specify which version to use, if desired. If it is not specified, the default is to use the latest Python version for the current architecture (x86 or x64). This default can be customized through a py.ini file or PY_PYTHON environment variable. See the docs for more details.
Newer versions of Python update the launcher. The latest version has a py -0 option to list the installed Pythons and indicate the current default.
Here's how to check if the launcher is registered correctly from the console:
C:\>assoc .py
.py=Python.File
C:\>ftype Python.File
Python.File="C:\Windows\py.exe" "%1" %*
Above, .py files are associated with the Python.File type. The command line for Python.File is the Python Launcher, which is installed in the Windows directory since it is always in the PATH.
For the association to work, run scripts from the command line with script.py, not "python script.py", otherwise python will be run instead of py. If fact it's best to remove Python directories from the PATH, so "python" won't run anything and enforce using py.
py.exe can also be run with switches to force a Python version:
py -3 script.py # select latest Python 3.X version to be used.
py -3.6 script.py # select version 3.6 specifically.
py -3.9-32 script.py # select version 3.9 32-bit specifically.
py -0 # list installed Python versions (latest PyLauncher).
Additionally, add .py;.pyw;.pyc;.pyo to the PATHEXT environment variable and then the command line can just be script with no extension.

Running 'py' command will tell you what version you have running. If you currently running 3.x and you need to switch to 2.x, you will need to use switch '-2'
py -2
If you need to switch from python 2.x to python 3.x you will have to use '-3' switch
py -3
If you would like to have Python 3.x as a default version, then you will need to create environment variable 'PY_PYTHON' and set it's value to 3.

If you know about Environment variables and the system variable called path, consider that any version of any binary which comes sooner, will be used as default.
Look at the image below, I have 3 different python versions but python 3.8 will be used as default since it came sooner than the other two. (In case of mentioned image, sooner means higher!)

If you are a Windows user and you have a version of Python 3.3 or greater, you should have the Python Launcher for Windows installed on your machine, which is the recommended way to use for launching all python scripts (regardless of python version the script requires).
As a user
Always type py instead of python when running a script from the command line.
Setup your "Open with..." explorer default program association with C:\Windows\py.exe
Set the command line file extension association to use the Python Launcher for Windows (this will make typing py optional). In an Admin cmd terminal, run:
ftype Python.File="C:\Windows\py.exe" "%L" %*
ftype Python.NoConFile="C:\Windows\pyw.exe" "%L" %*
Set your preferred default version by setting the PY_PYTHON environment variable (e.g. PY_PYTHON=3.11). You can see what version of python is your default by typing py. You can also set PY_PYTHON3 or PY_PYTHON2 to specify default python 3 and python 2 versions (if you have multiple).
If you need to run a specific version of python, you can use py -M.m (where M is the major version and m is the minor version). For example, py -3 will run any installed version of python 3.
List the installed versions of python with py -0.
As a script writer
Include a shebang line at the top of your script that indicates the major version number of python required. If the script is not compatible with any other minor version, include the minor version number as well. For example:
#!/usr/bin/env python3
Note: (see this question) If python3 does not work for you, ensure that you've installed python from the Windows Store (e.g. via winget install --id 9NRWMJP3717K, as the winget package Python.Python.3.11 does not appear to include a python3.exe).
You can use the shebang line to indicate a virtual environment as well (see PEP 486 below).
See also
PEP 397 -- Python launcher for Windows
PEP 486 -- Make the Python Launcher aware of virtual environments
Python Launcher for Windows - User Guide

See here for original post
;
; This is an example of how a Python Launcher .ini file is structured.
; If you want to use it, copy it to py.ini and make your changes there,
; after removing this header comment.
; This file will be removed on launcher uninstallation and overwritten
; when the launcher is installed or upgraded, so don't edit this file
; as your changes will be lost.
;
[defaults]
; Uncomment out the following line to have Python 3 be the default.
;python=3
[commands]
; Put in any customised commands you want here, in the format
; that's shown in the example line. You only need quotes around the
; executable if the path has spaces in it.
;
; You can then use e.g. #!myprog as your shebang line in scripts, and
; the launcher would invoke e.g.
;
; "c:\Program Files\MyCustom.exe" -a -b -c myscript.py
;
;myprog="c:\Program Files\MyCustom.exe" -a -b -c
Thus, on my system I made a py.ini file under c:\windows\ where py.exe exists, with the following contents:
[defaults]
python=3
Now when you Double-click on a .py file, it will be run by the new default version. Now I'm only using the Shebang #! python2 on my old scripts.

Edit registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\python.exe\default
Set default program to open .py files to python.exe

This work for me.
If you want to use the python 3.6 you must move the python3.6 on the top of the list.
The same applies to the python2.7
If you want to have the 2.7 as default then make sure you move the python2.7 on the very top on the list.
step 1
step 2
step 3
then close any cmd command prompt and opened again, it should work as expected.
python --version
>>> Python 3.6

This worked for me:
Go to
Control Panel\System and Security\System
select
Advanced system settings from the left panel
from Advanced tab click on Environment Variables
In the System variables section search for (create if doesn't exist)
PYTHONPATH
and set
C:\Python27\;C:\Python27\Scripts;
or your desired version
You need to restart CMD.
In case it still doesn't work you might want to leave in the PATH variable only your desired version.

With Python version 2.7, 3.7, 3.9 and 3.11 installed on my Windows 11 OS, the above solutions didn't works for me.
The command py --help give some hints to set python version, example:
usage:
[...]
If an exact version is not given, using the latest
version can be overridden by any of the following, (in priority
order):
👉 From [defaults] in py.ini in your %LOCALAPPDATA%\py.ini
The easiest way I found to set a specific default Python version is to create/edit a py.ini file under %LOCALAPPDATA%\py.ini.
Content of py.ini 👇
[defaults]
python=3.7
Console output with Administrator and User right 💡:
C:\Users\bob>py --version
Python 3.7.9

If you are on Windows, use the ASSOC command to change the default python version for python programs.
assoc .py=<Python 3.1 directory>

Now that Python 3.3 is released it is easiest to use the py.exe utility described here:
http://www.python.org/dev/peps/pep-0397/
It allows you to specify a Python version in your script file using a UNIX style directive. There are also command line and environment variable options for controlling which version of Python is run.
The easiest way to get this utility is to install Python 3.3 or later.

Nothing above worked, this is what worked for me:
ftype Python.File=C:\Path\to\python.exe "%1" %*
This command should be run in Command prompt launched as administrator
Warning: even if the path in this command is set to python35, if you have python36 installed it's going to set the default to python36. To prevent this, you can temporarily change the folder name from Python36 to xxPython36, run the command and then remove the change to the Python 36 folder.
Edit: This is what I ended up doing: I use Python Launcher.
https://stackoverflow.com/a/68139696/3154274

Check which one the system is currently using:
python --version
Add the main folder location (e.g. C/ProgramFiles) and Scripts location (C/ProgramFiles/Scripts) to Environment Variables of the system. Add both 3.x version and 2.x version
Path location is ranked inside environment variable. If you want to use Python 2.x simply put path of python 2.x first, if you want for Python 3.x simply put 3.x first
This uses python 2

Since my problem was slightly different and none of the above worked for me, I'll add what worked for me. I had installed the new python launcher for python 3.10 today, installed the version through it, but the command window did not recognise the version. Instead, it listed older python3 versions I had on my computer.
Finally, in the windows programs list, I saw that I had two versions of the python launcher. I uninstalled the old one, and now python 3.10 shows up correctly when running py -0 and is the chosen version when running py.
Apologies if this is a noob answer, I am new to all this.

I had same problem and solve it by executing the installation file again. when you do that python automatically knows you have installed it before so it recommends you 3 options! select modify and select all packages you want to modify then in the next page you can check if new version of python is added to your environment variables or not. check it and then execute modification. I did and it solved.

Use SET command in Windows CMD to temporarily set the default python for the current session.
SET PATH=C:\Program Files\Python 3.5

Try modifying the path in the windows registry (HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment).
Caveat: Don't break the registry :)

Pyperclip module installed but not found when program runs from cmd

I wrote a program that use pyperclip module and it would work from Pycharm and python IDLE, would work as well if starting from Powershell but if I try to start the program from WIN+R, when launched, the program returns an error saying that pyperclip module is not installed. The same problem appears when I run it from the Anaconda Powershell Prompt.
PLEASE NOTICE:
The program was working perfectly before I installed Anaconda and Jupyterlab.
The error occurs when I run the program from the cmd using WIN+R AND when I run it from the Anaconda Command Prompt but it's fine when run from IDLE, Powershell, Pycharm.
I always used python 3 and only yesterday I installed Anaconda.
Thanks for the help!

I just spent couple of hours trying to solve exactly the same problem. What I found out is that, as couple of members have already pointed out, the main problem is the mismatch between the version of the python that runs in cmd and the versions of the python used in scripts/batch files.
The first line in the code, known as "shebang", in .py file indicates the version of the python that the script should use when it is executed. So, it must match the version run by default with cmd (or when executed with win+R). In my case, I also have a batch file (.bat) that calls specified version of the python, which should be the same version used with .py file.
The problem was that both of my files (.py and .bat) were calling python 3.8 while the cmd is running version 3.7. Initially, I used shebang #! python3 in my .py file, and command #py path/to/python/file.py %* (and I also tried #py.exe path/to/python/file.py %*) in my .bat file, and that did not work.
To solve the problem, I updated these two files to link to python version 3.7 with following:
changed shebang in .py file to #! python
changed command in .bat file to #python path/to/python/file.py %*
With these changes the system runs the program with win+R.

whew, taking course on python and instructor had py.exe instead of python.exe in .bat call. despite trying all of the other installation methods others have mentioned, just changing this to python.exe did that trick.

Python 3.2 doesn't work with python 2.7

I already have python 2.7 (installed using activepython). I'm trying to use python 3.2 just to learn more about it so i downloaded it from python.org
python 2.7 still works perfectly, but python 3.2 gives me this error when i try to open the ide.
and then I see the send error window, if i install python 3.2 using activepython i see the same error.
I'm using windows xp pro sp3 32 bit and i had the same error on sp2... How do I fix it?
EDIT #Zuljin
This is the first time that i use dependancy walker so could you give me a hand please
this is what i see
what does that mean? I already have these files...

I saw a lot of answers here. But, I think the file that you are trying to run is not correct
C:\Python32\Pythonw.exe
is not the one you use to open idle.
Open
C:\Python32\Lib\idlelib\idle.pyw

Python 2.x and 3.x can cohabitate perfectly in win xp and win 7, either 32 or 64 bits.
If you first installed the ActiveState Python distribution, be careful when installing python-3.2.2.msi.
When you arrive to the customize python 3.2.2 screen, (un)check 'register extensions' to make the feature unavailable (that is: do not register extensions).
I have installed this way both distributions in different computers without any problem so far.
Note: Check your environment variables. Only python 2.7 should be in the path (if you installed before the two distros you could have them both in the path. Remove python 3.2 path)
Edit:
From Ankit post I realized that in fact you were trying to open IDLE, maybe.
If you follow my installation instructions when you call idle.bat from the py3.2 idlelib folder you actually get idle for python 2.7 as this is what the call find in the windows path. To be able to open idle for py3.2 in the presence of python 2.7 as the registered python, I use a .bat file modified from that in the distribution:
idle_stay.bat
#echo off
rem Working IDLE bat for Windows - Custom bat for py3k as secundary python
C:\Python32\pythonw C:\Python32\Lib\idlelib\idle.pyw %1 %2 %3 %4 %5 %6 %7 %8 %9
The name idle_stay.bat is because I put this file in the folder where the official idle.bat is (C:\Python32\Lib\idlelib\idle_stay.bat). In this way it does not get overwritten each time I unisntall and reinstall a new version of python 3

It seems to me you have associated a *.py or *.pyw file extension type to some version of python.exe and/or pythonw.exe you aren't clear about. This is often, but not exclusively done from within Microsoft's "explore.exe" File Manager (I believe in Options).
I disagree that this is a reliable method:
C:\Python32\Lib\idlelib\idle.pyw
as this method will run whichever program is assigned to the "pyw" extension. That could be:
C:\Python32\pythonw.exe
or
C:\Python26\python.exe
or whatever might have happened to your file extension association as per OS or bad PATH environment variable setting. It is better to do something like this:
C:\Python32\pythonw.exe C:\Python32\Lib\idlelib\idle.pyw
where you are explicidly telling the OS to run the python executable from a specific path and selecting a specific python script in the file/folder hiearchy.
Another thing you can try to gather info is just:
python.exe -V
which will tell you the version number.
Another thing you can do:
Open a DOS command prompt and type:
set PATH=C:\Windows;C:\Windows\system32;C:\Python32
python.exe and note the version and whether is runs.
exit()
exit
Once working debug your PATH. You can use this Python script to gather intel.
If you turned off your WinXP findfile stuff (like I have) you can use this script:
inpath.py can help shed some light.
Run this python script like this:
Drop to a DOS prompt
cd to your folder with a working python.exe version.
and type python.exe inpath.py python*
where inpath is in that same folder for this test/debug.
inpath.py will search your path for all files associated as "runable" in your OS and that is in your "PATH" with the python*.* pattern.

How Should I Set Default Python Version In Windows?

I installed Python 2.6 and Python 3.1 on Windows 7 and set environment variable: path = d:\python2.6.
When I run python in cmd, it displays the python version 2.6, which is what I want!
But, when I wrote a script in a bat file and ran it, the displayed python version was 3.1.
import sys
print (sys.version)
What's going on here?

This is if you have both the versions installed.
Go to This PC → Right-click → Click on Properties → Advanced System Settings.
You will see the System Properties. From here navigate to the Advanced Tab -> Click on Environment Variables.
You will see a top half for the user variables and the bottom half for System variables.
Check the System Variables and double-click on the Path (to edit the Path).
Check for the path of Python(which you wish to run i.e. Python 2.x or 3.x) and move it to the top of the Path list.
Restart the Command Prompt, and now when you check the version of Python, it should correctly display the required version.

Running 'py' command will tell you what version you have running. If you currently running 3.x and you need to switch to 2.x, you will need to use switch '-2'
py -2
If you need to switch from python 2.x to python 3.x you will have to use '-3' switch
py -3
If you would like to have Python 3.x as a default version, then you will need to create environment variable 'PY_PYTHON' and set it's value to 3.

If you know about Environment variables and the system variable called path, consider that any version of any binary which comes sooner, will be used as default.
Look at the image below, I have 3 different python versions but python 3.8 will be used as default since it came sooner than the other two. (In case of mentioned image, sooner means higher!)

See here for original post
;
; This is an example of how a Python Launcher .ini file is structured.
; If you want to use it, copy it to py.ini and make your changes there,
; after removing this header comment.
; This file will be removed on launcher uninstallation and overwritten
; when the launcher is installed or upgraded, so don't edit this file
; as your changes will be lost.
;
[defaults]
; Uncomment out the following line to have Python 3 be the default.
;python=3
[commands]
; Put in any customised commands you want here, in the format
; that's shown in the example line. You only need quotes around the
; executable if the path has spaces in it.
;
; You can then use e.g. #!myprog as your shebang line in scripts, and
; the launcher would invoke e.g.
;
; "c:\Program Files\MyCustom.exe" -a -b -c myscript.py
;
;myprog="c:\Program Files\MyCustom.exe" -a -b -c
Thus, on my system I made a py.ini file under c:\windows\ where py.exe exists, with the following contents:
[defaults]
python=3
Now when you Double-click on a .py file, it will be run by the new default version. Now I'm only using the Shebang #! python2 on my old scripts.

Edit registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\python.exe\default
Set default program to open .py files to python.exe

This work for me.
If you want to use the python 3.6 you must move the python3.6 on the top of the list.
The same applies to the python2.7
If you want to have the 2.7 as default then make sure you move the python2.7 on the very top on the list.
step 1
step 2
step 3
then close any cmd command prompt and opened again, it should work as expected.
python --version
>>> Python 3.6

This worked for me:
Go to
Control Panel\System and Security\System
select
Advanced system settings from the left panel
from Advanced tab click on Environment Variables
In the System variables section search for (create if doesn't exist)
PYTHONPATH
and set
C:\Python27\;C:\Python27\Scripts;
or your desired version
You need to restart CMD.
In case it still doesn't work you might want to leave in the PATH variable only your desired version.

With Python version 2.7, 3.7, 3.9 and 3.11 installed on my Windows 11 OS, the above solutions didn't works for me.
The command py --help give some hints to set python version, example:
usage:
[...]
If an exact version is not given, using the latest
version can be overridden by any of the following, (in priority
order):
👉 From [defaults] in py.ini in your %LOCALAPPDATA%\py.ini
The easiest way I found to set a specific default Python version is to create/edit a py.ini file under %LOCALAPPDATA%\py.ini.
Content of py.ini 👇
[defaults]
python=3.7
Console output with Administrator and User right 💡:
C:\Users\bob>py --version
Python 3.7.9

If you are on Windows, use the ASSOC command to change the default python version for python programs.
assoc .py=<Python 3.1 directory>

Now that Python 3.3 is released it is easiest to use the py.exe utility described here:
http://www.python.org/dev/peps/pep-0397/
It allows you to specify a Python version in your script file using a UNIX style directive. There are also command line and environment variable options for controlling which version of Python is run.
The easiest way to get this utility is to install Python 3.3 or later.

Nothing above worked, this is what worked for me:
ftype Python.File=C:\Path\to\python.exe "%1" %*
This command should be run in Command prompt launched as administrator
Warning: even if the path in this command is set to python35, if you have python36 installed it's going to set the default to python36. To prevent this, you can temporarily change the folder name from Python36 to xxPython36, run the command and then remove the change to the Python 36 folder.
Edit: This is what I ended up doing: I use Python Launcher.
https://stackoverflow.com/a/68139696/3154274

Check which one the system is currently using:
python --version
Add the main folder location (e.g. C/ProgramFiles) and Scripts location (C/ProgramFiles/Scripts) to Environment Variables of the system. Add both 3.x version and 2.x version
Path location is ranked inside environment variable. If you want to use Python 2.x simply put path of python 2.x first, if you want for Python 3.x simply put 3.x first
This uses python 2

Since my problem was slightly different and none of the above worked for me, I'll add what worked for me. I had installed the new python launcher for python 3.10 today, installed the version through it, but the command window did not recognise the version. Instead, it listed older python3 versions I had on my computer.
Finally, in the windows programs list, I saw that I had two versions of the python launcher. I uninstalled the old one, and now python 3.10 shows up correctly when running py -0 and is the chosen version when running py.
Apologies if this is a noob answer, I am new to all this.

I had same problem and solve it by executing the installation file again. when you do that python automatically knows you have installed it before so it recommends you 3 options! select modify and select all packages you want to modify then in the next page you can check if new version of python is added to your environment variables or not. check it and then execute modification. I did and it solved.

Use SET command in Windows CMD to temporarily set the default python for the current session.
SET PATH=C:\Program Files\Python 3.5

Try modifying the path in the windows registry (HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment).
Caveat: Don't break the registry :)

How to install both Python 2.x and Python 3.x in Windows

I do most of my programming in Python 3.x on Windows 7, but now I need to use the Python Imaging Library (PIL), ImageMagick, and wxPython, all of which require Python 2.x.
Can I have both Python 2.x and Python 3.x installed in Windows 7? When I run a script, how would I "choose" which version of Python should run it? Will the aforementioned programs be able to handle multiple versions of Python installed at once? I have searched for hours and hours for how to do this to no avail.
Thanks.

I found that the formal way to do this is as follows:
Just install two (or more, using their installers) versions of Python on Windows 7 (for me work with 3.3 and 2.7).
Follow the instuctions below, changing the parameters for your needs.
Create the following environment variable (to default on double click):
Name: PY_PYTHON
Value: 3
To launch a script in a particular interpreter, add the following shebang (beginning of script):
#! python2
To execute a script using a specific interpreter, use the following prompt command:
> py -2 MyScript.py
To launch a specific interpreter:
> py -2
To launch the default interpreter (defined by the PY_PYTHON variable):
> py
Resources
Documentation: Using Python on Windows
PEP 397 - Python launcher for Windows

What I did was download both 2.7.6 and 3.3.4. Python 3.3.4 has the option to add the path to it in the environment variable so that was done. So basically I just manually added Python 2.7.6.
How to...
Start > in the search type in environment select "Edit environment variables to your account"1
Scroll down to Path, select path, click edit.
Add C:\Python27;
so you should have paths to both versions of Python there, but if you don't this you can easily edit it so that you do..... C:\Python27;C:\Python33;
Navigate to the Python27 folder in C:\ and rename a copy of python.exe to python2.exe
Navigate to the Python34 folder in C:\ and rename a copy of python.exe to python3.exe
Test: open up commmand prompt and type python2 ....BOOM! Python 2.7.6. exit out.
Test: open up commmand prompt and type python3 ....BOOM! Python 3.4.3. exit out.
Note: (so as not to break pip commands in step 4 and 5, keep copy of python.exe in the same directory as the renamed file)

I have multiple versions in windows.
I just change the exe name of the version I'm not defaulting to.
python.exe --> python26.exe
pythonw.exe --> pythonw26.exe
As for package installers, most exe installers allow you to choose the python install to add the package too.
For manual installation check out the --prefix option to define where the package should be installed:
http://docs.python.org/install/index.html#alternate-installation-windows-the-prefix-scheme

If you use Anaconda Python, you can easily install various environments.
Say you had Anaconda Python 2.7 installed and you wanted a python 3.4 environment:
conda create -n py34 python=3.4 anaconda
Then to activate the environment:
activate py34
And to deactive:
deactivate py34
(With Linux, you should use source activate py34.)
Links:
Download Anaconda Python
Instructions for environments

To install and run any version of Python in the same system follow my guide below.
For example say you want to install Python 2.x and Python 3.x on the same Windows system.
Install both of their binary releases anywhere you want.
When prompted do not register their file extensions and
do not add them automatically to the PATH environment variable
Running simply the command python the executable that is first met in PATH will be chosen for launch. In other words, add the Python directories manually. The one you add first will be selected when you type python. Consecutive python programs (increasing order that their directories are placed in PATH) will be chosen like so:
py -2 for the second python
py -3 for the third python etc..
No matter the order of "pythons" you can:
run Python 2.x scripts using the command: py -2 (Python 3.x functionality) (ie. the first Python 2.x installation program found in your PATH will be selected)
run Python 3.x scripts using the command: or py -3 (ie. the first Python 3.x installation program found in your PATH will be selected)
In my example I have Python 2.7.14 installed first and Python 3.5.3. This is how my PATH variable starts with:
PATH=C:\Program Files\Microsoft MPI\Bin\;C:\Python27;C:\Program Files\Python_3.6\Scripts\;C:\Program Files\Python_3.6\;C:\ProgramData\Oracle\Java\javapath;C:\Program Files (x86)\Common Files\Intel\Shared
...
Note that Python 2.7 is first and Python 3.5 second.
So running python command will launch python 2.7 (if Python 3.5 the same command would launch Python 3.5).
Running py -2 launches Python 2.7 (because it happens that the second Python is Python 3.5 which is incompatible with py -2).
Running py -3 launches Python 3.5 (because it's Python 3.x)
If you had another python later in your path you would launch like so: py -4. This may change if/when Python version 4 is released.
Now py -4 or py -5 etc. on my system outputs: Requested Python version (4) not installed or Requested Python version (5) not installed etc.
Hopefully this is clear enough.

Here's what you can do:
Install cmder.
Open and use Cmder as you would with you cmd terminal.
Use the command alias to create command aliases.
I did the following:
alias python2 = c:\python27\python.exe
alias python3 = c:\python34\python.exe
And that's it! ;-)

I actually just thought of an interesting solution. While Windows will not allow you to easily alias programs, you can instead create renamed batch files that will call the current program.
Instead of renaming the executable which will break a lot of thing including pip, create the file python2.bat in the same directory as the python2.exe. Then add the following line:
%~dp0python %*
What does this archaic syntax mean? Well, it's a batch script, (Windows version of bash). %~dp0 gets the current directory and %* will just pass all the arguments to python that were passed to the script.
Repeat for python3.bat
You can also do the same for pip and other utilities, just replace the word python in the file with pip or whathever the filename. The alias will be whatever the file is named.
Best of all, when added to the PATH, Windows ignores the extension so running
python3
Will launch the python3 version and and the command python2 will launch the python2 version.
BTW, this is the same technique Spyder uses to add itself to the path on Windows. :)

Starting version 3.3 Windows version has Python launcher, please take a look at section 3.4. Python Launcher for Windows

You can install multiple versions of Python one machine, and during setup, you can choose to have one of them associate itself with Python file extensions. If you install modules, there will be different setup packages for different versions, or you can choose which version you want to target. Since they generally install themselves into the site-packages directory of the interpreter version, there shouldn't be any conflicts (but I haven't tested this). To choose which version of python, you would have to manually specify the path to the interpreter if it is not the default one. As far as I know, they would share the same PATH and PYTHONPATH variables, which may be a problem.
Note: I run Windows XP. I have no idea if any of this changes for other versions, but I don't see any reason that it would.

What I have done on my own windows computer where I have Python 2.7 and Python 3.4 installed is I wrote a simple .bat file in the same directory as my Python.exe files. They look something like,
cmd /k "c:\python27\python.exe" %*
The %* allows you to add arguments (Python files) afterwards. I believe /k keeps the prompt open after it finishes running the script. Then I save that as python27.bat Then I go to my Python 3 directory and make a bat file there. Now in my command line I can write
Python27 helloworld.py
Or
Python34 helloworld.py
And they will run in their respective versions of Python. Make sure that c:\python27 and c:\python34 are in your environment variables.
I got my answer from here

I did this in three steps by following the instructions here: This is all taken directly from here: http://ipython.readthedocs.io/en/stable/install/kernel_install.html. I'm currently running Python 2.x on Windows 8 and have Anaconda 4.2.13 installed.
1) First install the latest version of python:
conda create -n python3 python=3 ipykernel
2) Next activate python3
activate python3
3) Install the kernel:
python -m ipykernel install --user
If you have Python 3 installed and want to install 2, switch the 2 and the 3 above. When you open a new notebook, you can now choose between Python 2 or 3.

Check your system environment variables after installing Python, python 3's directories should be first in your PATH variable, then python 2.
Whichever path variable matches first is the one Windows uses.
As always py -2 will launch python2 in this scenario.

I have encountered that problem myself and I made my launchers in a .bat so you could choose the version you want to launch.
The only problem is your .py must be in the python folder, but anyway here is the code:
For Python2
#echo off
title Python2 Launcher by KinDa
cls
echo Type the exact version of Python you use (eg. 23, 24, 25, 26)
set/p version=
cls
echo Type the file you want to launch without .py (eg. hello world, calculator)
set/p launch=
path = %PATH%;C:\Python%version%
cd C:\Python%version%
python %launch%.py
pause
For Python3
#echo off
title Python3 Launcher by KinDa
cls
echo Type the exact version of Python you use (eg. 31, 32, 33, 34)
set/p version=
cls
echo Type the file you want to launch without .py (eg. hello world, calculator)
set/p launch=
cls
set path = %PATH%:C:\Python%version%
cd C:\Python%version%
python %launch%.py
pause
Save them as .bat and follow the instructions inside.

Install the one you use most (3.3 in my case) over the top of the other. That'll force IDLE to use the one you want.
Alternatively (from the python3.3 README):
Installing multiple versions
On Unix and Mac systems if you intend to install multiple versions of Python
using the same installation prefix (--prefix argument to the configure script)
you must take care that your primary python executable is not overwritten by the
installation of a different version. All files and directories installed using
"make altinstall" contain the major and minor version and can thus live
side-by-side. "make install" also creates ${prefix}/bin/python3 which refers to
${prefix}/bin/pythonX.Y. If you intend to install multiple versions using the
same prefix you must decide which version (if any) is your "primary" version.
Install that version using "make install". Install all other versions using
"make altinstall".
For example, if you want to install Python 2.6, 2.7 and 3.3 with 2.7 being the
primary version, you would execute "make install" in your 2.7 build directory
and "make altinstall" in the others.

I just had to install them. Then I used the free (and portable) soft at http://defaultprogramseditor.com/ under "File type settings"/"Context menu"/search:"py", chose .py file and added an 'open' command for the 2 IDLE by copying the existant command named 'open with IDLE, changing names to IDLE 3.4.1/2.7.8, and remplacing the files numbers of their respective versions in the program path. Now I have just to right click the .py file and chose which IDLE I want to use. Can do the same with direct interpreters if you prefer.

I use a simple solution to switch from a version to another version of python, you can install all version you want. All you have to do is creating some variable environment.
In my case, I have installed python 2.7 and python 3.8.1, so I have created this environment variables:
PYTHON_HOME_2.7=<path_python_2.7>
PYTHON_HOME_3.8.1=<path_python_3.8.1>
PYTHON_HOME=%PYTHON_HOME_2.7%
then in my PATH environment variable I put only %PYTHON_HOME% and %PYTHON_HOME%\Scripts. In the example above I'm using the version 2.7, when I want to switch to the other version I have only to set the PYTHON_HOME=%PYTHON_HOME_3.8.1%.
I use this method to switch quickly from a version to another also for JAVA, MAVEN, GRADLE,ANT, and so on.

Only Works if your running your code in your Python IDE
I have both Python 2.7 and Python 3.3 installed on my windows operating system. If I try to launch a file, it will usually open up on the python 2.7 IDE. How I solved this issue, was when I choose to run my code on python 3.3, I open up python 3.3 IDLE(Python GUI), select file, open my file with the IDLE and save it. Then when I run my code, it runs to the IDLE that I currently opened it with. It works vice versa with 2.7.

I have installed both python 2.7.13 and python 3.6.1 on windows 10pro and I was getting the same "Fatal error" when I tried pip2 or pip3.
What I did to correct this was to go to the location of python.exe for python 2 and python 3 files and create a copy of each, I then renamed each copy to python2.exe and python3.exe depending on the python version in the installation folder. I therefore had in each python installation folder both a python.exe file and a python2.exe or python3.exe depending on the python version.
This resolved my problem when I typed either pip2 or pip3.

If you can't get anything else to work, open an interpreter in whichever version you choose (I prefer using iPython) and:
import subprocess
subprocess.call('python script.py -flags')
This uses whichever python version you are currently operating under. Works fine for a single script, but will quickly get out of hand if there are lots of scripts you run, in which case you can always make a batch file with all of these calls inside. Not the most elegant answer, but it works.
Is there a way to make aliases for different python version a la Linux?

Develop Reference

Python is a programming language that lets you work quickly and integrate systems more effectively.