[FIXED] Pythonic way to write a for loop that doesn't use the loop index

Issue

This is to do with the following code, which uses a for loop to generate a series of random offsets for use elsewhere in the program.

The index of this for loop is unused, and this is resulting in the 'offending' code being highlighted as a warning by Eclipse / PyDev

def RandomSample(count):    
    pattern = []
    for i in range(count):
        pattern.append( (random() - 0.5, random() - 0.5) )

    return pattern

So I either need a better way to write this loop that doesn't need a loop index, or a way to tell PyDev to ignore this particular instance of an unused variable.

Does anyone have any suggestions?

Solution

randomSample = [(random() - 0.5, random() - 0.5) for _ in range(count)]

Sample output, for count=10 and assuming that you mean the Standard Library random() function:

[(-0.07, -0.40), (0.39, 0.18), (0.13, 0.29), (-0.11, -0.15),\
(-0.49, 0.42), (-0.20, 0.21), (-0.44, 0.36), (0.22, -0.08),\
(0.21, 0.31), (0.33, 0.02)]

If you really need to make it a function, then you can abbreviate by using a lambda:

f = lambda count: [(random() - 0.5, random() - 0.5) for _ in range(count)]

This way you can call it like:

>>> f(1)
f(1)
[(0.03, -0.09)]
>>> f(2)
f(2)
[(-0.13, 0.38), (0.10, -0.04)]
>>> f(5)
f(5)
[(-0.38, -0.14), (0.31, -0.16), (-0.34, -0.46), (-0.45, 0.28), (-0.01, -0.18)]
>>> f(10)
f(10)
[(0.01, -0.24), (0.39, -0.11), (-0.06, 0.09), (0.42, -0.26), (0.24, -0.44) , (-0.29, -0.30), (-0.27, 0.45), (0.10, -0.41), (0.36, -0.07), (0.00, -0.42)]
>>> 

you get the idea...

Answered By - Escualo
Answer Checked By - Mildred Charles (JavaFixing Admin)