Reading A File With Fortran Formatted Small Floats, Using Numpy

I am trying to read a data file written by a Fortran program, in which every once in a while there is a very small float like 0.3299880-104. The error message is: >np.loadtxt(fi

Solution 1:

As @agentp mentioned in the comments, one approach would be to use the converters= argument to np.genfromtxt to insert the e characters before casting to float:

import numpy as np

# some example strings
strings = "0.3299880-104 0.3299880+104 0.3299880"

# create a "dummy file" (see http://stackoverflow.com/a/11970414/1461210)
try:
    from StringIO import StringIO     # Python2
    f = StringIO(strings)
except ImportError:
    from io import BytesIO            # Python3
    f = BytesIO(strings.encode())

c = lambda s: float(s.decode().replace('+', 'e').replace('-', 'e-'))

data = np.genfromtxt(f, converters=dict(zip(range(3), [c]*3)))

print(repr(data))
# array([  3.29988000e-105,   3.29988000e+103,   3.29988000e-001])