Change working directory in shell with a python script

That is not going to be possible.

Your script runs in a sub-shell spawned by the parent shell where the command was issued.

Any cding done in the sub-shell does not affect the parent shell.

Others have pointed out that you can't change the working directory of a parent from a child.

But there is a way you can achieve your goal -- if you cd from a shell function, it can change the working dir. Add this to your ~/.bashrc:

go() {
    cd "$(python /path/to/cd.py "$1")"
}

Your script should print the path to the directory that you want to change to. For example, this could be your cd.py:

#!/usr/bin/python
import sys, os.path
if sys.argv[1] == 'tdi': print(os.path.expanduser('~/long/tedious/path/to/tdi'))
elif sys.argv[1] == 'xyz':  print(os.path.expanduser('~/long/tedious/path/to/xyz'))

Then you can do:

tdi@bayes:/home/$> go tdi
tdi@bayes:/home/tdi$> go tdi

cd is exclusively(?) implemented as a shell internal command, because any external program cannot change parent shell's CWD.

As codaddict writes, what happens in your sub-shell does not affect the parent shell. However, if your goal is to present the user with a shell in a different directory, you could always have Python use os.chdir to change the sub-shell's working directory and then launch a new shell from Python. This will not change the working directory of the original shell, but will leave the user with one in a different directory.