Python packages are located in differente location

Question

• I am using Ubuntu 20.04 which comes python 3.8.
• I installed python3.9 and made it as default python update-alternatives
• under /usr/bin/ I have python2.7/ python3/ python3.8/ and python3.9/

==> Now the problem that I am facing is when I installed sqlalchemy using pip install sqlalchemy its version was 1.3.12, which has a compatibility problem with pandas because it requires version '1.4.0'.

>>>pip install --upgrade sqlalchemy

>>> Defaulting to user installation because normal site-packages is not writeable
Requirement already satisfied: sqlalchemy in /usr/lib/python3/dist-packages (1.3.12)
Collecting sqlalchemy
  Downloading SQLAlchemy-1.4.31-cp38-cp38-manylinux_2_5_x86_64.manylinux1_x86_64.manylinux_2_17_x86_64.manylinux2014_x86_64.whl (1.6 MB)
     ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 1.6/1.6 MB 8.3 MB/s eta 0:00:00
Collecting greenlet!=0.4.17
  Downloading greenlet-1.1.2-cp38-cp38-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (156 kB)
     ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 156.6/156.6 KB 9.6 MB/s eta 0:00:00
Installing collected packages: greenlet, sqlalchemy
Successfully installed greenlet-1.1.2 sqlalchemy-1.4.31

I wrote the same command again it gave me this :

Defaulting to user installation because normal site-packages is not writeable
Requirement already satisfied: sqlalchemy in ./.local/lib/python3.8/site-packages (1.4.31)
Requirement already satisfied: greenlet!=0.4.17 in ./.local/lib/python3.8/site-packages (from sqlalchemy) (1.1.2)

I also did this to check:

>>>pip show sqlalchemy | grep Location

>>>Location: /home/Moe/.local/lib/python3.8/site-packages

but when I import sqlalchemy in a script it still uses the old version it seems that the new version is installed in a different location

>>> print(sqlalchemy.__file__)

>>>/usr/lib/python3/dist-packages/sqlalchemy/__init__.py

Can Someone please explain this to me, and if possible explain the entire package management problem here

Answer 1

You are calling pip that is associated with your python 3.8, you can see that in the whl file that is downloaded:

Downloading SQLAlchemy-1.4.31-cp38-cp38-manylinux_2_5_x86_64.manylinux1_x86_64.manylinux_2_17_x86_64.manylinux2014_x86_64.whl

Note the cp38

And in the output of running the install again:

Requirement already satisfied: sqlalchemy in ./.local/lib/python3.8/site-packages (1.4.31)

Note the python3.8.

Since you have mentioned that you downloaded python 3.9, you are probably running your scripts using that version of python. You will need to use the pip that is associated with that python. If you are running your script with

python <scriptfile>

Then you should pip install with

python -m pip install ...