Getting output from "print" inside a function [duplicate]

Question

Im using a library of functions that some of them print data I need:

def func():
   print "data"

How can I call this function and get the printed data into a string?

You can't... Try return "data" which is the only way to go. Unless you want to catch the output of another python script, then you can use x = subprocess.Popen("python script.py", shell=True") and then x.stdout.read(). Might (and i mean might.. only thought about it for a second) be able to use eval() to call the function and there catch the output.. But wouldn't reccomend it.. — Torxed
– Torxed, Commented Feb 20, 2014 at 14:18
yes... well I want to avoid changing the library code. If ther really is no way, I will copy paste into my code and use return — WeaselFox
– WeaselFox, Commented Feb 20, 2014 at 14:19
When using Python3, you could override the print function and have it collect the data somewhere else. — tobias_k
– tobias_k, Commented Feb 20, 2014 at 14:20
dis.dis() also uses print; see the linked duplicate on how you could work around that. — Martijn Pieters
– Martijn Pieters, Commented Feb 20, 2014 at 14:21

Tim Pietzcker · Accepted Answer · 2014-02-20 14:22:41Z

10

If you can't change those functions, you will need to redirect sys.stdout:

>>> import sys
>>> stdout = sys.stdout
>>> import StringIO
>>> s = StringIO.StringIO()
>>> sys.stdout = s
>>> print "hello"
>>> sys.stdout = stdout
>>> s.seek(0)
>>> s.read()
'hello\n'

answered Feb 20, 2014 at 14:22

Tim Pietzcker

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2 Comments

WeaselFox Over a year ago

I could use this solution.. not very elegant though. thanks

ccy Over a year ago

If you want to use it Python3, you should change the 3rd line as "from io import StringIO", and the 4th line as "s = StringIO()".

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