Is there a way to step between 0 and 1 by 0.1?
I thought I could do it like the following, but it failed:
for i in range(0, 1, 0.1): print i
Instead, it says that the step argument cannot be zero, which I did not expect.
Rather than using a decimal step directly, it's much safer to express this in terms of how many points you want. Otherwise, floating-point rounding error is likely to give you a wrong result.
You can use the
linspace function from the NumPy library (which isn't part of the standard library but is relatively easy to obtain).
linspace takes a number of points to return, and also lets you specify whether or not to include the right endpoint:
>>> np.linspace(0,1,11) array([ 0. , 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1. ]) >>> np.linspace(0,1,10,endpoint=False) array([ 0. , 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9])
If you really want to use a floating-point step value, you can, with
>>> import numpy as np >>> np.arange(0.0, 1.0, 0.1) array([ 0. , 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9])
Floating-point rounding error will cause problems, though. Here's a simple case where rounding error causes
arange to produce a length-4 array when it should only produce 3 numbers:
>>> numpy.arange(1, 1.3, 0.1) array([1. , 1.1, 1.2, 1.3])
Python's range() can only do integers, not floating point. In your specific case, you can use a list comprehension instead:
[x * 0.1 for x in range(0, 10)]
(Replace the call to range with that expression.)
For the more general case, you may want to write a custom function or generator.