Equally-spaced numbers (linspace) (Python)

2015-01-12T22:16:37-08:00

Python recipe 579000 by Andrew Barnert (float, linspace, range, spread).

An equivalent of numpy.linspace, but as a pure-Python lazy sequence.

Like NumPy's linspace, but unlike the spread and frange recipes listed here, the num argument specifies the number of values, not the number of intervals, and the range is closed, not half-open.

Although this is primarily designed for floats, it will work for Fraction, Decimal, NumPy arrays (although this would be silly) and even datetime values.

This recipe can also serve as an example for creating lazy sequences.

See the discussion below for caveats.

"Comma float" to float (Python)

2010-02-11T22:19:41-08:00

Python recipe 577054 by Matevz Lesko (comma, float, numbers, string). Revision 2.

Convert comma separated floating point number (12,3456) to float.

Generate equally-spaced floats (Python)

2011-09-24T18:49:39-07:00

Python recipe 577878 by Steven D'Aprano (float, range, spread).

Generating a list of equally-spaced floats can surprising due to floating point rounding. See, for example, the recipe for a floating point range. One way of avoiding some surprises is by changing the API: instead of specifying a start, stop and step values, instead use a start, stop and count:

>>> list(spread(0.0, 2.1, 7))
[0.0, 0.3, 0.6, 0.9, 1.2, 1.5, 1.8]

Like frange spread takes an optional mode argument to select whether the start and end values are included. By default, start is included and end is not, and exactly count values are returned.

Floating point range (Python)

2010-02-24T07:12:55-08:00

Python recipe 577068 by Steven D'Aprano (float, math, maths, range).

Generator that produces floats, equivalent to range for integers, minimising rounding errors by using only a single multiplication and addition for each number, and no divisions.

This generator takes an optional argument controlling whether it produces numbers from the open, closed, or half-open interval.

Floating point bitwise operations (Python)

2011-11-28T23:47:25-08:00

Python recipe 577967 by Pyry Pakkanen (bitwise, float, floating, point).

Implements bitwise operations for real numbers by using an infinite one's complement representation.

Special Range Function for Different Kinds of Ranges (int, float, character) (Python)

2011-03-30T16:42:47-07:00

Python recipe 577583 by Sunjay Varma (character, float, integer, python, range, special). Revision 3.

This module allows the user to create a more verbose set of ranges. Simple character ranges, and float ranges are supported.

Supported Ranges:

Basic Integer Ranges
Float Ranges (as accurate as a float range can get)
Simple character ranges (lowercase to lowercase, uppercase to uppercase, etc.)

It should work in Python 2 and Python 3.

If you tested this for speed, or want to test this for speed, please post the results! (And your system specs)

Edit: Found a really silly error of mine when using range instead of xrange in these functions!

Function that supports dividing timedelta by float (Python)

2012-05-17T13:47:07-07:00

Python recipe 578136 by Ben Hoyt (datetime, division, float).

Python 2.x doesn't support dividing a timedelta by a float (only works with int). This function adds support for that.

Improved range function (Python)

2010-06-07T01:50:20-07:00

Python recipe 577256 by Sunjay Varma (float, python, range, replace). Revision 2.

While using the built-in range function a while ago. I found an odd (perhaps bug) where the range function couldn't use float steps. I am not sure if that was intended for simplicity or not, but I wrote my own range function that goes beyond that anyway.

How to Mutate a Float (Python)

2012-05-14T16:49:13-07:00

Python recipe 578132 by Stephen Chappell (ctypes, experiment, float, structure).

This is just an experiment to test my mental understanding of Python. It should not be used in any code as is violates the design principle that floats are to be immutable. The code also abuses ctypes and an understanding of how floats are currently arranged in memory. set_float is not guaranteed to work properly on any system, and may fail to work in the future if the data's arrangement changes.

Equally-spaced floats part 2 (Python)

2011-09-27T15:48:00-07:00

Python recipe 577881 by Steven D'Aprano (float, range, spread).

See the recipe here for a description of the problem.

This variant allows the user to choose between two APIs, either by supplying the count, start value and end value:

>>> list(spread(5, 1.0, end=2.0))
[1.0, 1.2, 1.4, 1.6, 1.8]

or the count, start value and step size:

>>> list(spread(5, 1.0, step=-0.25))
[1.0, 0.75, 0.5, 0.25, 0.0]

As before, the count argument specifies how many subdivisions are made. The optional argument mode selects whether the start and end values are included. By default, start is included and end is not, and exactly count values are returned.

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