Python - computed value is always 0.0

Question

I have a basic loop as follows:

for x in range(81,346):
    print float(((x - 81)/(346-81))*100)
    # DO STUFF

The thing is, the output I get is 0.0 for all values. I checked to see that x-81 is giving the correct output. I also replaced 346-81 as 265. But for some reason, all output is being given as 0.0.
Any suggestions as to what is going wrong?

You are seeing this problem - http://stackoverflow.com/questions/2958684/python-division. Use floats as intermediate results to fix the issue - `print float(((x - 81.0)/(346-81))*100)` — Nikola Dimitroff, Dec 13 '15 at 23:05
FYI this behavior has changed in Python3. Python3 does float division by default. It also introduced integer division operator `//` — Kenji Noguchi, Dec 13 '15 at 23:14

timgeb · Answer 1 · 2015-12-13T23:11:05.013

4

You are performing integer division. Change 81 to 81.0 or cast the numerator or denominator to float.

edited Dec 13 '15 at 23:11

answered Dec 13 '15 at 23:05

timgeb

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So typecasting doesn't work? `float(346-81)` would also work? – Kanishka Ganguly Dec 13 '15 at 23:06
@KanishkaGanguly typecasting will also work, just make sure to cast before the division happens. – timgeb Dec 13 '15 at 23:06

score 3 · Answer 2 · answered Dec 13 '15 at 23:17

3

Python 2 uses integer division on integers. It was a bad idea and Python 3 fixed it. To have the (better) behaviour from future, put this in the beginning of your py file:

from __future__ import division

answered Dec 13 '15 at 23:17

zvone

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Python - computed value is always 0.0

2 Answers2