如何使用带有Matlab系统功能的Python处理“没有名为library_name的模块”错误？

Question

When I try to run a Python script in Matlab using the system command, it works find until I import something that doesn't come with base Python.

For example, if I have a script test_1.py:

import math as m
print 'good to go'
print m.exp(7)

and I run the Matlab command:

>>> system('python test_1.py')

I get back

good to go
1096.63315843

ans = 

    0

which is what I want. But if I modify test_1.py to be

import math as m
import pandas as pd
print 'good to go'
print m.exp(7)

and run

>>> system('python test_1.py')

I get:

>> system('python test_1.py')
Traceback (most recent call last):
  File "test_1.py", line 1, in <module>
    import pandas as pd
ImportError: No module named pandas

ans =

     1

Both scripts run fine when I run them in my Bash terminal and the problem doesn't seem to be specific to the Pandas library.

I checked Matlab's documentation and some other StackOverflow questions but I can't find anything closely related to my issue.

Answer 1

When installing Anaconda with default settings, it will automatically add the Anaconda binaries to your $PATH variable. If you choose not to, you can add it manually by adding the following line to your .bashrc (or .bash_profile on Mac) file:

export PATH="/home/username/anaconda/bin:$PATH" 

Now, in your case, this has happened (in either way), so Anaconda does work in your bash shell. On Mac OS X, however, there are two different $PATH variables: the bash path, and the launchctl path. The bash path is used if you open a terminal, or run a program from the terminal. The launchctl path is used when you run a program "the normal way", which is with the launchctl command. Now, your bash path is correct, but your launchctl path isn't - that is why it works in a terminal, but not from MATLAB.

You can either set the launchctl path to be the same as the bash path, by adding the following line to your .bash_profile :

launchctl setenv PATH $PATH

This changes the path settings for all programs, which might be undesirable. So, it might be easiest and safest to add the Anaconda binaries to the path from within MATLAB with the path function, at the start of your script:

path('Users/JackStClaire/anaconda/bin/', path)

By adding it to the beginning of your $PATH variable, which makes sure that it uses the Anaconda python and not the system python .

Answer 2

In the Matlab script you can simply set the environment that Python use to communicate with its libraries to be sure that it is the right one

PATH_PYTHON = '/Users/matteofabris/anaconda2/lib/python2.7/site-packages/';
setenv('PYTHONPATH', PATH_PYTHON);