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Using pip on Windows installed with both python 2.7 and 3.5

I am using Windows 10. Currently, I have Python 2.7 installed. I would like to install Python 3.5 as well. However, if I have both 2.7 and 3.5 installed, when I run pip, how do I get the direct the package to be installed to the desired Python version?

You will have to use the absolute path of pip.
E.g: if I installed python 3 to C:\python35, I would use:
C:\> python35\Scripts\pip.exe install packagename
Or if you're on linux, use pip3 install packagename
If you don't specify a full path, it will use whichever pip is in your path.

Because usually i change my intepreter to run something(i got 2 diff projects with both 2 and 3), i use these solution:
Add path to the environment as usual (of course)
Rename ur python.exe , in my case i want to run python 3 using command python3 on my cmd. So i renamed my python.exe in python3.x directory with python3. Itll works with python 2 ofc.
Then to use pip in both python, i use this command.
python3 -m pip install 'somepackage'
and to run pip on python2
python -m pip install 'somepackage'
This is may not the best solution out there, but i like this one
** WINDOWS **
ref : https://datascience.com.co/how-to-install-python-2-7-and-3-6-in-windows-10-add-python-path-281e7eae62a

In my case, I have Python 2.7 and Python 3.4, with the Python Launcher for Windows.
This is the output when running this commands:
PS C:\> pip -V
pip 9.0.1 from c:\python27\lib\site-packages (python 2.7)
PS C:\> pip3 -V
pip 9.0.1 from C:\Python34\lib\site-packages (python 3.4)
I'll note that in my Python27\Scripts\ directory, I have pip.exe, pip2.exe and pip2.7.exe.
And in my Python34\Scripts\ directory, I have pip.exe, pip3.exe and pip3.4.exe.
So all of these .exe files help you when you have different versions of Python installed at the same time.
Of course, for this to work, you have to have the respective Scriptsdirectries in your Path system enviroment variable.

The answer from Farhan.K will work. However, I think a more convenient way would be to rename python35\Scripts\pip.exe to python35\Scripts\pip3.exe assuming python 3 is installed in C:\python35.
After renaming, you can use pip3 when installing packages to python v3 and pip when installing packages to python v2. Without the renaming, your computer will use whichever pip is in your path.

I would advise against ever calling any pip script directly (nor pip3, pip2.7.exe, anything like that).
Instead, a surefire way is to always prefer the explicit variant of calling pip's executable module for a specific Python interpreter:
path/to/pythonX.Y -m pip somecommand
path/to/venv/bin/python -m pip somecommand
C:\path\to\venv\Scripts\python.exe -m pip somecommand
There are many advantages to this, for example:
It is explicit for which Python interpreter the projects will be pip-installed (Python 2 or 3, inside the virtual environment or not, etc.)
For a virtual environment, one can pip-install (or do other things) without activating it: path/to/venv/bin/python -m pip install SomeProject
Under Windows this is the only way to safely upgrade pip itself path\to\venv\Scripts\python.exe -m pip install --upgrade pip
But yes, if all is perfectly setup, then python3 -m pip install SomeProject and pip3 install SomeProject should do the exact same thing, but there are way too many cases where there is an issue with the setup and things don't work as expected and users get confused (as shown by the many questions about this topic on this platform).
References
Brett Cannon's article "Why you should use python -m pip"
pip's documentation section on "Upgrading pip"
venv's documentation section on "Creating virtual environments": "You don’t specifically need to activate an environment [...]"

I ran across an issue with running pip with absolute path. This might be related to WinPython's installation routine and the order of installing Python 3.6 first, 2.7 second, or Python 3.6 being in the path.
No matter which pip was called, it was activating the 3.6 one:
λ C:\prog\WinPython-64bit-2.7.13.1Zero\python-2.7.13.amd64\Scripts\pip2.exe --version
pip 9.0.1 from C:\prog\WinPython-64bit-3.6.1.0Zero\python-3.6.1.amd64\lib\site-packages (python 3.6)
What finally did the trick was calling pip as a module of the respective python binary:
λ C:\prog\WinPython-64bit-2.7.13.1Zero\python-2.7.13.amd64\python.exe -m pip --version
pip 9.0.1 from C:\prog\WinPython-64bit-2.7.13.1Zero\python-2.7.13.amd64\lib\site-packages (python 2.7)
Hope that might help someone with similar issues.

I tried many things , then finally
pip3 install --upgrade pip worked for me as i was facing this issue since i had both python3 and python2.7 installed on my system.
mind the pip3 in the beginning and pip in the end.
And yes you do have to run in admin mode the command prompt and make sure if the path is set properly.

1-open command prompt and change direction using the command cd C:\Python35\Scripts
2- write the command pip3 install --upgrade pip
3- close the command prompt and reopen it again to return to the default direction and use the command pip3.exe install package_name to install any package you want

How to change Python version in which modules get installed?

I'm trying to install Python-Twitch for Python 3.4. I have both 3.4 and 3.5 installed on my computer, and in command prompt I do this:
python --version
Where it gives me Python 3.5.x. Then:
set PATH=C:\Python34\;%PATH%
And python --version will then read Python 3.4.x.
Once I do 'pip install python-twitch', it installs it to the Python 3.5 Lib/Site-Packages folder. How would I get this over to 3.4?
Thanks so much for any help.

I think this was already answered: pip: dealing with multiple Python versions?
Since version 0.8, Pip supports pip-{version}. You can use it the same as easy_install-{version}:
$ pip-2.5 install myfoopackage
$ pip-2.6 install otherpackage
$ pip-2.7 install mybarpackage
EDIT: pip changed its schema to use pipVERSION instead of pip-VERSION in version 1.5. You should use the following if you have pip >= 1.5:
$ pip2.6 install otherpackage
$ pip2.7 install mybarpackage
Check https://github.com/pypa/pip/pull/1053 for more details

Pip suddenly using wrong version of Python

Having a weird problem with pip on os x.
As far as I can recall (and a quick look at my .bash_history seems to confirm) I have not made any recent changes to my configuration. Alas, the pip command seems to be suddenly using a different version of python than it was previously. Up until now I was using the command pip to manage my python2 libraries and pip3 to manage by python3 libraries. Suddenly, any attempts at running pip install fails with errors like missing parenthesis around print statements.
Here is the result of a few commands I attempted to figure out the problem:
which pip > /usr/local/bin/pip
which pip3 > /usr/local/bin/pip3
which python > /usr/local/bin/python
python version > Python 2.7.11
pip --version > pip 8.1.1 from /usr/local/lib/python3.5/site-packages (python 3.5)
So for some reason the pip command seems to be running from the PyPi2 database but in python3 now? Any ideas how to fix this?

I run with multiple Python versions and thus multiple pip versions as well.
Everytime, however, you update pip, you'll replace the standard pip command with the version you updated. So even pip3 install --upgrade pip will put a /usr/local/bin/pip in your system, messing up the Python 2 version.
Instead, I run pip as an (executable) module:
python3 -m pip search <package>
or
python2 -m pip search <package>
or even
python3.5 -m pip search <package>
This guarantees that your pip version always matches the Python version you want to use it for. It's somewhat longer to type, but I prefer the expliciteness of it (which, I guess, follows the Zen of Python).
Note that updating pip:
python3.5 -m pip install --upgrade pip
will still install a Python 3.5 version in /usr/local/bin/pip, but I'm simply ignoring that. Just beware of (shell) scripts that execute pip directly.

Find absolute path to Python you'd like to use:
which python
Open your default pip executable script:
vi $(which pip)
You will see a shebang line at the top which may point to wrong Python (i had that once too).
Point to the Python you want (see step 1), e.g.:
#!/usr/local/bin/python3.7

Try setting aliases by running the following commands in Terminal,
alias pip="/usr/local/bin/pip"
alias pip2="/usr/local/bin/pip"
alias pip3="/usr/local/bin/pip3"
If this solves your problem then you need to add the aliases in your bash profile.
Look How do I create a Bash alias? for more info.
Alternatively, you have to reinstall pip using python2 get-pip.py first and then python3 get-pip.py get-pip.py can be downloaded here https://bootstrap.pypa.io/get-pip.py

I had exactly the same problem!
I reinstall python2 by brew brew reinstall python#2
after reinstall, pip install packagename works!

None of these worked for me so what I did was navigate to
C:\Users(User)\AppData\Local\Programs\Python\
and deleted all the old python versions I wasn't using. (Worked)

How to install pip with a specific python version

I want to install pip for python 2.7, but I am also having python 3.x but both locations are different. when ever I install or update the pip It is installing in the python 3.x location.
How to install pip for python 2.7?

I recently found the following solution, when you are maintaining python2.x and python 3.x in host system. You can find the pip under Scripts folder.
Try pip --version it gives pip version and python version as well
If you want to install package using pip use the following commands.
python -m pip install package_name
python2.x -m pip install package_name
Which reads the specified python pip module to install the package

Installing pip with correct python version

I am on shared hosting and I need to install pip with the correct python version, 2.7. To install pip, I did:
$ easy_install pip
However, after it was installed I get the following:
[dave#web1 lib]$ pip --version
pip 1.0.2 from /home/premiere/dave/financials/lib/pip-1.0.2-py2.7.egg (python 2.4)
How would I re-install pip to work on the python2.7 version, which is also installed on the machine?
[premiered#web1 ~]$ python --version
Python 2.6.6
Which is strange, since it is installing to python2.4.

You may want to create a virtualenv using -p /path/to/python-2.7.binary param, and then activate it. Then all stuff you installed using pip would be correctly into your virtualenv.

If multiple versions of python are installed on the system, then you should invoke the version you want when installing. i.e.
$ python27 easy_install pip
This creates a pip file in your path that contains the specified version of python in the hashBang line.