floating_in_text.md

Formats for floating point values in text files

.. testsetup::

    import numpy as np
    # Set print options for doctests below
    np.set_printoptions(precision=6)

Let's say we have a floating point numbers like this:

a_number = 314.15926 a_number 314.15926

We can also represent these numbers in exponential format. Exponential format breaks the number into a two parts: the significand; and the exponent.

The significand is a floating point number with one digit before a decimal point. The exponent is an integer. For example:

exp_number = 3.1415926E2 exp_number 314.15926

Here the significand is 3.1415926, and the exponent is 2, the value after the E. The number is given by s * 10 ** e where s is the significand and e is the exponent. In this case: 314.15926 = 3.1415926 \* 10 ** 2.

This exponential format is the default format that np.savetxt uses to represent floating point numbers when writing to text files. For example:

import numpy as np an_array = np.array([a_number, 1.0, 2.0]) an_array array([ 314.15926, 1. , 2. ]) np.savetxt('some_numbers.txt', an_array) with open('some_numbers.txt', 'rt') as fobj: ... contents = fobj.read() print(contents) 3.141592600000000175e+02 1.000000000000000000e+00 2.000000000000000000e+00 <BLANKLINE>

.. testcleanup::

    import os
    os.unlink('some_numbers.txt')