Check helmet test data for Software Carpentry. See http://software-carpentry.org/2012/04/solution-to-data-checking-problem/.

helmet_test.py

"""
Check helmet test data for Software Carpentry.

"""

import sys
from collections import namedtuple


HelmetTest = namedtuple('HelmetTest', ['temp', 'time', 'brittle'])


def read_data_file(filename):
    """
    Get data from a text file.
    
    """
    test_results = []
    
    with open(filename, 'r') as f:
        f.readline()
        f.readline()
        
        for line in f:
            temp, time, brittle = line.split()
            
            h = HelmetTest(float(temp), float(time), float(brittle))
            
            test_results.append(h)
    
    return test_results


def read_data_stdin():
    """
    Get data from stdin.
    
    """
    test_results = []

    line = raw_input('temp time brittle: ')

    while line.strip():
        temp, time, brittle = line.split()
            
        h = HelmetTest(float(temp), float(time), float(brittle))
            
        test_results.append(h)
        
        line = raw_input('temp time brittle: ')
    
    return test_results


def format_error(test, prev_test):
    """
    Make the string reporting the error.
    
    """
    err_str = 'Error: ({}, {}, {}) inconsistent with ({}, {}, {})'
    
    return err_str.format(test.temp, test.time, test.brittle,
                          prev_test.temp, prev_test.time, prev_test.brittle)


def check_data(data):
    """
    Check data for consistency.
    
    """
    for i,test in enumerate(data):
        for prev_test in data[:i][::-1]:
            if test.time >= prev_test.time and test.brittle < prev_test.brittle:
                print format_error(test, prev_test)
                return
            
            if test.temp == prev_test.temp and test.brittle < prev_test.brittle:
                print format_error(test, prev_test)
                return


def main(filename=None):
    if filename:
        data = read_data_file(filename)
    else:
        data = read_data_stdin()
    
    check_data(data)


if __name__ == '__main__':
    if len(sys.argv[1:]) > 1:
        print 'helmet.py takes at most one argument.'
        sys.exit()
    
    if len(sys.argv[1:]) == 1:
        filename = sys.argv[1]
    else:
        filename = None
    
    sys.exit(main(filename))