format_rounded.py

format_rounded.py

# formatter for arrays of floating point numbers
# Rudi Farkas 8 Aug 2014

def format_rounded(float_arr, decimals=2, general=False, sep=', '):
    """
    Formats elements of float_arr with the stated number of decimal digits,
    in the fixed '%f' or general '%g' format.
    Returns the element strings joined with the separator.
    """
    return sep.join(['{:.{precision}{type}}'.format(x, precision=decimals, type='g' if general else 'f') for x in float_arr])


if __name__ == '__main__':
    import unittest

    class T(unittest.TestCase):

        def test_format_rounded_fixed_and_general(self):
            arr1 = [i/3 for i in range(6)]
            self.assertEqual(format_rounded(arr1, decimals=3), '0.000, 0.333, 0.667, 1.000, 1.333, 1.667')
            self.assertEqual(format_rounded(arr1, decimals=3, general=True), '0, 0.333, 0.667, 1, 1.33, 1.67')
            arr2 = [1/3/10**i for i in range(6)]
            self.assertEqual(format_rounded(arr2, decimals=4, sep='  '), '0.3333  0.0333  0.0033  0.0003  0.0000  0.0000')
            self.assertEqual(format_rounded(arr2, decimals=4, general=True), '0.3333, 0.03333, 0.003333, 0.0003333, 3.333e-05, 3.333e-06')

    unittest.main()