Possible Duplicate:
Python decimal range() step value
I would like generate list like this:
[0, 0.05, 0.1, 0.15 ... ] range(0, 1, 0.05) would be great but it doesn't work beacuse:
range() integer step argument expected, got float.
Have you any elegant idea? ;)
If you can use numpy, it's a good idea to use numpy.linspace. Functions that try to fit range logic on floating-point numbers, including numpy's own arange, usually get confusing regarding whether the end boundary ends up in the list or not. linspace elegantly resolves that by having you to explicitly specify the start point, the end point, and the desired number of elements:
>>> import numpy >>> numpy.linspace(0.0, 1.0, 21) array([ 0. , 0.05, 0.1 , 0.15, 0.2 , 0.25, 0.3 , 0.35, 0.4 , 0.45, 0.5 , 0.55, 0.6 , 0.65, 0.7 , 0.75, 0.8 , 0.85, 0.9 , 0.95, 1. ]) 
linspace might get confusing about how many items are there ("why 21 and not 20?"). True that a comment would always be in order anyway.
20 to 21 after my initial example failed to work as expected. :) Still, this kind of confusion is much less subtle and prone to surprises than the confusion of whether the end point gets included in the range (and how to always make it there if it's not). It's always a tradeoff, but at least here it's obvious that you get what you asked for — len of the resulting array is 21.
endpoint argument.In Python 3, range returns a generator (immutable sequence)... so I think we can define a very simple function like:
def frange(start,stop, step=1.0): while start < stop: yield start start +=step So:
for x in frange(0, 1, 0.05): print(x) Python doesn't need to be tricky.
If you want a list, just call:
list(frange(0,1,0.05)) Or change the function to return a list right away.
You can use one line solutions that multiply or do other stuff, but it can be tricky with different start and end values. If you use this kind of ranges frequently, just use the function and reuse it. Even a one-liner repeated many times on code is bad.
Or how about this:
[v*0.05 for v in range(0,int(1/0.05))] 
[v*0.05 for v in range(0,20)], I just tried to show that one liner is possible :)
How about this:
temp = range(0,100,5) # 0,5,10,...,95 final_list = map(lambda x: x/100.0,temp) # becomes 0,0.05,0.10,...,0.95 It's not very elegant, but I've never bothered into making a proper function. Also, it only works if the step size is rational. The advantage is that it's quick enough to be done on the spot.
See comments to your OP for a more general and more elegant solution.
What's wrong with
[i/100.0 for i in range(0, 100, 5)] ? You check how many digits you want (here two) and whip out a suitable multiplier (1 becomes 100, 0.05 becomes 5).
