cmpfloat.py

#!/usr/bin/python3
#-*-python-*-
'''Compare two files while tolerating small errors in floating point numbers.
Written by Hao Chen, 2015'''
import sys, shlex, argparse

def makeshlex(filename):
    myshlex = shlex.shlex(open(filename), filename, True)
    # For decimal and scientific notation float
    myshlex.wordchars='0123456789.-+eE'
    myshlex.whitespace=''
    return myshlex

def notequal(f1, f2):
    return (abs(f1 - f2) * 0x400) > max(abs(f1), abs(f2), 1)

def differ(file1, file2):
    if not options.silent:
        print('{} {} differ'.format(file1, file2), file=sys.stderr)

parser = argparse.ArgumentParser(
    description='Compare two files ignoring small differences in float point values.')
parser.add_argument('-s', '--silent', action = 'store_true',
                    default = False,
                    help = 'Output nothing; yield exit status only.')
parser.add_argument('-d', '--debug', action = 'store_true',
                    default = False,
                    help = 'Debug mode. Output tokens.')
parser.add_argument('file1', type=str)
parser.add_argument('file2', type=str)
options = parser.parse_args()

filename1 = options.file1
filename2 = options.file2
file1 = makeshlex(filename1)
file2 = makeshlex(filename2)

t1 = file1.get_token()
t2 = file2.get_token()
while t1 is not None and t2 is not None:
    f1 = None
    f2 = None
    try:
        f1 = float(t1)
        f2 = float(t2)
    except ValueError:
        pass
    if f1 is None or f2 is None:
        # f1 and/or f2 are not float
        if t1 != t2:
            differ(filename1, filename2)
            exit(1)
    else:
        # both f1 and f2 are float
        if options.debug:
            print('{}:{}:'.format(t1,t2), file=sys.stderr)
        if notequal(f1, f2):
            differ(filename1, filename2)
            exit(1)
    t1 = file1.get_token()
    t2 = file2.get_token()

if t1 is None and t2 is None:
    exit(0)
else:
    differ(filename1, filename2)
    exit(1)