floatrange’s documentation!

floatrange - range() like with float numbers.

author:Laurent Pointal <laurent.pointal@laposte.net>
copyright:Laurent Pointal, 2011-2015

Usage example

(note computation approximation and display with floats)

>>> from floatrange import floatrange
>>> floatrange(5)
floatrange(0.0, 5.0, 1.0)
>>> list(floatrange(5))
[0.0, 1.0, 2.0, 3.0, 4.0]
>>> list(floatrange(3.2,5.4,0.2))
[3.2, 3.4000000000000004, 3.6, 3.8000000000000003, 4.0, 4.2, 4.4,
4.6000000000000005, 4.800000000000001, 5.0, 5.2]
>>> 6 in floatrange(1,8)
>>> 6.1 in floatrange(1,8,1,prec=0.2)
>>> 6.1 in floatrange(1,8,1,prec=0.05)
>>> list(reversed(floatrange(5)))
[4.0, 3.0, 2.0, 1.0, 0.0]
>>> list(floatrange(10.1,9.7,-0.1))
[10.1, 10.0, 9.9, 9.799999999999999]

floatrange class

class floatrange.floatrange([start, ]stop[, step[, prec]]) → floatrange object

Build a virtual sequence of floating point numbers from start to stop by step. Set float equality precision with prec (default 0 for strict equality).

Unlike Python range(), generated values are floating point. Like Python range(), the stop value is not included (to have the stop value included, just add step*0.1 to it).

A floatrange object is usable like Python range, to iterate on the values, to test for its length, to get the value at an index, to get length of values sequence, to search for the index of a value, to count the number of occurrences of a value.

As floating point computation may lead to slightly different values, you should take care:

  • Test for presence of a value in the range use prec, which is by default zero for exact equality.
  • When reverting the floatrange, the new object is created to generate reverse values, this can build values with computational differences. To have exact same values in reverse order, cast to a list and reverse it.

Other solutions

If you have the scipy’s numpy package installed, see numpy.arange() and numpy.linspace() functions (docs for arange and linspace). If you have heavy computation, this is the way to go.

Note these differences between numpy functions and floatrange:

  • floatrange generate values when needed, like range().
  • floatrange has a precision parameter prec to deal with inaccurate floating point computation.
  • floatrange is a pure Python module.

And searching for Python float range, or frange will give you other solutions (see also comments on these solutions when available).