Develop Reference

OS X "which python" points to python2.7 instead of Anaconda python3.9

I factory reset my MacBook and set up everything new to get rid of the multiple python version chaos I had on my old laptop.
Only thing I have installed atm is Anaconda. I created a new conda environment with python 3.9 and activated it in my zsh Terminal.
Still when I type "which python" it shows "/usr/bin/python" containing the MacBook standard Python2.7 version.
How can I make environments use their own dedicated version?
Edit for Code:
conda activate myenvname
which python
Trying to access the folder where the anaconda python should be leads to
cd: no such file or directory: /Users/marcus/anaconda/bin

When you install anaconda through the terminal it provides an option to prepend anaconda to the system path. make sure to choose yes. If you don't, you'll need to provide the full path to your anaconda installation when activating an environment, as in:
source <path to conda>/bin/activate
conda init
You'll need to do this in each shell session. Alternatively, you can use the anaconda terminal.
To fix this, Anaconda does not recommend fixing your path manually. I think this is because there are a number of things anaconda does when setting up your shell if you choose "yes". Instead, the recommended fix is to uninstall and re-install anaconda (and pick yes this time ;)).
See the Anaconda docs for more information.

ipython uses wrong python version with anaconda

After activating my anaconda Python 3.6 environment with
source activate py36
if I type
python
I go into python 3.6, as expected. But if I type
ipython
I go into an ipython environment based python 3.5.5, which is the same python version I get using
source activate base
and then
python
How can I get into an ipython environment using my anaconda-supplied python 3.6 interpreter? I have updated my anaconda environment with
conda update anaconda
and
conda update conda
Doing so does not help.
EDIT:
I hadn't realized that I had to install ipython separately for the python 3.6 environment; I'd thought it was a default part of anaconda. So
conda install ipython
after
source activate py36
did the trick. It doesn't seem optimal that after activating a particular environment, ipython may bring up a completely different anaconda-based environment. I'd prefer it to simply cause a "command not found" error. Bringing up the wrong environment without making it very obvious that that is happening could lead to confusion or problems.

I hadn't realized that I had to install ipython separately for the python 3.6 environment; I'd thought it was a default part of anaconda. So
conda install ipython
after
source activate py36
did the trick.

Have you done hash -r since entering the conda environment? Bash can cache paths to executables, so sometimes it doesn't use the one reported by which. Running hash -r resets the cache
Maybe you need also to update ipython conda update ipython

conda not recognized in Anaconda Prompt after deactivating environment

Not sure if this is a bug, but if anyone has a suspected way to fix this issue, I would be eternally grateful.
Description
After activating an environment in the Anaconda Prompt, when I deactivate I seem to lose all conda-related information. In other words, it returns me to a normal Windows command prompt. (No Python, no conda commands, etc.) This is rather annoying because it means I need to open another Anaconda Prompt and navigate back to the folder where I was working.
Steps to reproduce:
Create a python environment with Anaconda Prompt
Activate it
Deactivate it
Try conda list
I just had 30 new users install Anaconda with Python 3.6 earlier this week, all on Windows, and they all experienced this issue. I have Miniconda, they have Anaconda.
Config info
platform : win-64
conda version : 4.3.25
python version : 3.6.1.final.0
EDIT: forgot to mention that I submitted a bug report just in case this was a bug. No responses at the moment.

Turns out, my understanding of deactivate was wrong -- it's purpose is to completely deactivate conda and remove all traces from the terminal. So this behavior is what deactivate is actually meant to do, not switch you to your root environment.
See the issue response here: link.

Run in Windows prompt:
cmd "/K" C:\ProgramData\Anaconda3\Scripts\activate.bat C:\ProgramData\Anaconda3
You will have anaconda prompt back.

Conda command is not recognized on Windows 10

I installed Anaconda 4.4.0 (Python 3.6 version) on Windows 10 by following the instructions here: https://www.continuum.io/downloads. However, when I open the Command prompt window and try to write
conda list
I get the
'conda' command is not recognized...
error.
I tried to run
set PATH=%PATH%;C:\Users\Alex\Anaconda3
but it didn't help. I also read that I might need to edit my .bashrc file, but I don't know how to access this file, and how I should edit it.

In Windows, you will have to set the path to the location where you installed Anaconda3 to.
For me, I installed anaconda3 into C:\Anaconda3. Therefore you need to add C:\Anaconda3 as well as C:\Anaconda3\Scripts\ to your path variable, e.g. set PATH=%PATH%;C:\Anaconda3;C:\Anaconda3\Scripts\.
You can do this via powershell (see above, https://msdn.microsoft.com/en-us/library/windows/desktop/bb776899(v=vs.85).aspx ), or hit the windows key → enter environment → choose from settings → edit environment variables for your account → select Path variable → Edit → New.
To test it, open a new dos shell, and you should be able to use conda commands now. E.g., try conda --version.

Things have been changed after conda 4.6.
Programs "Anaconda Prompt" and "Anaconda Powershell" expose the command conda for you automatically. Find them in your startup menu.
If you don't wanna use the prompts above and try to make conda available in a standard cmd.exe or a standard Powershell. Read the following content.
Expose conda in Every Shell
The purpose of the following content is to make command conda available both in cmd.exe and Powershell on Windows.
If you have already checked "Add Anaconda to my PATH environment variable" during Anaconda installation, skip step 1.
If Anaconda is installed for the current use only, add %USERPROFILE%\Anaconda3\condabin (I mean condabin, not Scripts) into the environment variable PATH (the user one). If Anaconda is installed for all users on your machine, add C:\ProgramData\Anaconda3\condabin into PATH.
How do I set system environment variables on Windows?
Open a new Powershell, run the following command once to initialize conda.
conda init
These steps make sure the conda command is exposed into your cmd.exe and Powershell.
Extended Reading: conda init from Conda 4.6
Caveat: Add the new \path\to\anaconda3\condabin but not \path\to\anaconda3\Scripts into your PATH. This is a big change introduced in conda 4.6.
Activation script initialization fron conda 4.6 release log
Conda 4.6 adds extensive initialization support so that more shells than ever before can use the new conda activate command. For more information, read the output from conda init –help We’re especially excited about this new way of working, because removing the need to modify PATH makes Conda much less disruptive to other software on your system.
In the old days, \path\to\anaconda3\Scripts is the one to be put into your PATH. It exposes command conda and the default Python from "base" environment at the same time.
After conda 4.6, conda related commands are separated into condabin. This makes it possible to expose ONLY command conda without activating the Python from "base" environment.
References
Conda 4.6 Release
How do I prevent Conda from activating the base environment?

When you install anaconda on windows now, it doesn't automatically add Python or Conda.
If you don’t know where your conda and/or python is, you type the following commands into your anaconda prompt
Next, you can add Python and Conda to your path by using the setx command in your command prompt.
Next close that command prompt and open a new one. Congrats you can now use conda and python
Source: https://medium.com/#GalarnykMichael/install-python-on-windows-anaconda-c63c7c3d1444

The newest version of the Anaconda installer for Windows will also install a windows launcher for "Anaconda Prompt" and "Anaconda Powershell Prompt". If you use one of those instead of the regular windows cmd shell, the conda command, python etc. should be available by default in this shell.

If you want to use Anaconda in regular cmd on windows you need to add several paths to your Path env variable.
Those paths are (instead of Anaconda3 the folder may be Anaconda2 depending on the Anaconda version on your PC):
\Users\YOUR_USER\Anaconda3
\Users\YOUR_USER\Anaconda3\Library\mingw-w64\bin
\Users\YOUR_USER\Anaconda3\Library\usr\bin
\Users\YOUR_USER\Anaconda3\Library\bin
\Users\YOUR_USER\Anaconda3\Scripts
\Users\YOUR_USER\Anaconda3\bin

I had also faced the same problem just an hour back. I was trying to install QuTip Quantum Toolbox in Python
Unfortunately, I didn't stumble onto this page in time.
Say you have downloaded Anaconda installer and run it until the end.
Naively, I opened the command prompt in windows 10 and proceded to type the following commands as given in the qutip installation docs.
conda create -n qutip-env
conda config --append channels conda-forge
conda install qutip
But as soon as I typed the first line I got the following response
conda is not recognized as an internal or external command, operable program or batch file
error messsage
I went ahead and tried some other things as seen in this figures
error message
Finally after going through a number conda websites, I understood how one fixes this problem.
Type Anaconda prompt in the search bar at the bottom like this (same place where you hail Cortana)
Anaconda prompt
Once you are here all the conda commands will work as usual

If you have installed Visual studio 2017 (profressional)
The install location:
C:\ProgramData\Anaconda3\Scripts
If you do not want the hassle of putting this in your path environment variable on windows and restarting you can run it by simply:
C:\>"C:\ProgramData\Anaconda3\Scripts\conda.exe" update qt pyqt

You need to add the python.exe in C://.../Anaconda3 installation file as well as C://.../Anaconda3/Scripts to PATH.
First go to your installation directory, in my case it is installed in C://Users/user/Anaconda3 and shift+right click and press "Open command window here" or it might be "Open powershell here", if it is powershell, just write cmd and hit enter to run command window. Then run the following command setx PATH %cd%
Then go to C://Users/user/Anaconda3/Scripts and open the command window there as above, then run the same command "setx PATH %cd%"

To prevent having further issues with SSL you should add all those to Path :
SETX PATH "%PATH%;C:\<path>\Anaconda3;C:\<path>\Anaconda3\Scripts;C:\<path>\Anaconda3\Library\bin"
Requests (Caused by SSLError("Can't connect to HTTPS URL because the SSL module is not available.") Error in PyCharm requesting website

case #1
You should set 3 path:
%ANACONDAPATH%;
%ANACONDAPATH%\Scripts;
%ANACONDAPATH%\Library\bin;
It will solve problem:
C:\WINDOWS\system32>conda update conda
Solving environment: failed
CondaHTTPError: HTTP 000 CONNECTION FAILED for url <https://repo.anaconda.com/pkgs/msys2/noarch/repodata.json.bz2>
Elapsed: -
...
case #2
Also you can use Anaconda Promd (for Win10) instead CLI (cmd.exe)

According to the official documentation, for Windows users there are two environment variable PATHs which can be updated, depending on how your Miniconda/Anaconda distribution has been installed -- one is the SYSTEM PATH, the other is the USER PATH: https://docs.conda.io/projects/conda/en/master/user-guide/tasks/manage-environments.html#activating-an-environment
Basically it says the following: If like the official recommendation you have installed conda for yourself on the user level only, you can add a path similar to C:\Users\<user-name>\miniconda3\Scripts to the user variables.
Please remember to change to Anaconda if you are not using miniconda and update the to your system username in order for this to work.
However, if you have a system level install for all users on the same machine, you should add the path c:\miniconda3\Scripts\ to the system variables.
Also, please run conda init in your PowerShell to have conda working on your PowerShell. If there is a Python version already installed on your PC, you can disable "app execution aliases" in Settings (under "Manage app execution aliases") for this to use only the Python ones on the command line to avoid conflict.

Even I got the same problem when I've first installed Anaconda. It said 'conda' command not found.
So I've just setup two values[added two new paths of Anaconda] system environment variables in the PATH variable which are: C:\Users\mshas\Anaconda2\ & C:\Users\mshas\Anaconda2\Scripts
Lot of people forgot to add the second variable which is "Scripts" just add that then conda command works.

'Conda' is not recognized as internal or external command

I installed Anaconda3 4.4.0 (32 bit) on my Windows 7 Professional machine and imported NumPy and Pandas on Jupyter notebook so I assume Python was installed correctly. But when I type conda list and conda --version in command prompt, it says conda is not recognized as internal or external command.
I have set environment variable for Anaconda3; Variable Name: Path, Variable Value: C:\Users\dipanwita.neogy\Anaconda3
How do I make it work?

I was faced with the same issue in windows 10, Updating the environment variable following steps, it's working fine.
I know It is a lengthy answer for the simple environment setups, I thought it's may be useful for the new window 10 users.
1) Open Anaconda Prompt:
2) Check Conda Installed Location.
where conda
3) Open Advanced System Settings
4) Click on Environment Variables
5) Edit Path
6) Add New Path
C:\Users\RajaRama\Anaconda3\Scripts
C:\Users\RajaRama\Anaconda3
C:\Users\RajaRama\Anaconda3\Library\bin
7) Open Command Prompt and Check Versions
8) After 7th step type
conda install anaconda-navigator in cmd then press y

Although you were offered a good solution by others I think it is helpful to point out what is really happening. As per the Anaconda 4.4 changelog, https://docs.anaconda.com/anaconda/reference/release-notes/#what-s-new-in-anaconda-4-4:
On Windows, the PATH environment variable is no longer changed by default, as this can cause trouble with other software. The recommended approach is to instead use Anaconda Navigator or the Anaconda Command Prompt (located in the Start Menu under “Anaconda”) when you wish to use Anaconda software.
(Note: recent Win 10 does not assume you have privileges to install or update. If the command fails, right-click on the Anaconda Command Prompt, choose "More", chose "Run as administrator")
This is a change from previous installations. It is suggested to use Navigator or the Anaconda Prompt although you can always add it to your PATH as well. During the install the box to add Anaconda to the PATH is now unchecked but you can select it.

I found the solution.
Variable value should be C:\Users\dipanwita.neogy\Anaconda3\Scripts

When you install anaconda on windows now, it doesn't automatically add Python or Conda to your path.
While during the installation process you can check this box, you can also add python and/or python to your path manually (as you can see below the image)
If you don’t know where your conda and/or python is, you type the following commands into your anaconda prompt
where python
where conda
Next, you can add Python and Conda to your path by using the setx command in your command prompt (replace C:\Users\mgalarnyk\Anaconda2 with the results you got when running where python and where conda).
SETX PATH "%PATH%;C:\Users\mgalarnyk\Anaconda2\Scripts;C:\Users\mgalarnyk\Anaconda2"
Next close that command prompt and open a new one. Congrats you can now use conda and python
Source: https://medium.com/#GalarnykMichael/install-python-on-windows-anaconda-c63c7c3d1444

Just to be clear, you need to go to the controlpanel\System\Advanced system settings\Environment Variables\Path,
then hit edit and add:
C:Users\user.user\Anaconda3\Scripts
to the end and restart the cmd line

In addition to adding C:\Users\yourusername\Anaconda3 and C:\Users\yourusername\Anaconda3\Scripts, as recommended by Raja (above), also add C:\Users\yourusername\Anaconda3\Library\bin to your path variable. This will prevent an SSL error that is bound to happen if you're performing this on a fresh install of Anaconda.

If you have a newer version of the Anaconda Navigator, open the Anaconda Prompt program that came in the install. Type all the usual conda update/conda install commands there.
I think the answers above explain this, but I could have used a very simple instruction like this. Perhaps it will help others.

Go To anaconda prompt(type "anaconda" in search box in your laptop). type following commands
where conda
add that location to your environment path variables. Close the cmd and open it again

This problem arose for me when I installed Anaconda multiple times. I was careful to do an uninstall but there are some things that the uninstall process doesn't undo.
In my case, I needed to remove a file Microsoft.PowerShell_profile.ps1 from ~\Documents\WindowsPowerShell\. I identified that this file was the culprit by opening it in a text editor. I saw that it referenced the old installation location C:\Anaconda3\.

For conda --version greater than 4.6, from the base of your Anaconda promt, run
conda update conda
conda init
This will update your conda root environment and setup the stuff you need to run it on both cwd and powershell.
After this, you can start any terminal and it will be conda ready.

If you don't want to add Anaconda to env. path and you are using Windows try this:
Open cmd;
Type path to your folder instalation. It's something like:
C:\Users\your_home folder\Anaconda3\Scripts
Test Anaconda, for exemple type conda --version.
Update Anaconda: conda update conda or conda update --all or conda update anaconda.
Update Spyder:
conda update qt pyqt
conda update spyder

I have Windows 10 64 bit, this worked for me,
This solution can work for both (Anaconda/MiniConda) distributions.
First of all try to uninstall anaconda/miniconda which is causing problem.
After that delete '.anaconda' and '.conda' folders from 'C:\Users\'
If you have any antivirus software installed then try to exclude all the folders,subfolders inside 'C:\ProgramData\Anaconda3\' from
Behaviour detection.
Virus detection.
DNA scan.
Suspicious files scan.
Any other virus protection mode.
*(Note: 'C:\ProgramData\Anaconda3' this folder is default installation folder, you can change it just replace your excluded path at installation destination prompt while installing Anaconda)*
Now install Anaconda with admin privileges.
Set the installation path as 'C:\ProgramData\Anaconda3' or you can specify your custom path just remember it should not contain any white space and it should be excluded from virus detection.
At Advanced Installation Options you can check "Add Anaconda to my PATH environment variable(optional)" and "Register Anaconda as my default Python 3.6"
Install it with further default settings. Click on finish after done.
Restart your computer.
Now open Command prompt or Anaconda prompt and check installation using following command
conda list
If you get any package list then the anaconda/miniconda is successfully installed.

I have just launched anaconda-navigator and run the conda commands from there.

For those who didn't check "Add Anaconda to my PATH environment variable". In Windows 10 it looks like that:
5 paths:
C:\Users\shtosh\anaconda3
C:\Users\shtosh\anaconda3\Library\mingw-w64\bin
C:\Users\shtosh\anaconda3\Library\usr\bin
C:\Users\shtosh\anaconda3\Library\bin
C:\Users\shtosh\anaconda3\Scripts

if you use chocolatey, conda is in C:\tools\Anaconda3\Scripts

I had this problem in windows. Most of the answers are not as recommended by anaconda, you should not add the path to the environment variables as it can break other things. Instead you should use anaconda prompt as mentioned in the top answer.
However, this may also break. In this case right click on the shortcut, go to shortcut tab, and the target value should read something like:
%windir%\System32\cmd.exe "/K" C:\Users\myUser\Anaconda3\Scripts\activate.bat C:\Users\myUser\Anaconda3