'''
weatherstats.py

Ben Cochran

This is my implementation of the weather stats assignment.

'''

import sys, math

def standardDeviation(listOfNumbers):
    '''Returns the standard deviation of the specified list of
        numbers if the list contains 2 or more elements.  Otherwise,
        returns 0.  This function assumes that its parameter refers
        to a (possibly empty) list of numbers.'''
    if len(listOfNumbers) == 0:
        return 0
        
    theMean = mean(listOfNumbers)
    squaresList = []
    for item in listOfNumbers:
        theSquare = item ** 2
        squaresList.append(theSquare)
        
    return math.sqrt(sum(squaresList) / float(len(squaresList)))

def mean(listOfNumbers):
    '''Returns the mean of the specified list of numbers
        if the list contains at least one element.  Otherwise,
        returns 0.  This function assumes that its parameter refers
        to a (possibly empty) list of numbers.'''
    if len(listOfNumbers) == 0:
        return 0
        
    theSum = sum(listOfNumbers)
    theMean = theSum / float(len(listOfNumbers))
    return theMean

def loadWeatherData(fileName):
    '''Loads temperature data from the specified file into a
        list of lists of integers, and returns the list.  This
        function assumes that each line of the file consists of
        a year followed by some number of temperatures, all
        separated by commas.  For example, if the file looks
        like this: 
        
            1939,-10,5,3,14,...
            1940,2,8,-1,4,...
            ...
            2008,7,12,3,5,-2,...
            
        (which means that on Jan 1, 1939, the high temperature
        was 10, etc.), then loadWeatherData will return a list
        of lists like this:
        
            [[1939,-10,5,3,14,...], [1940,2,...], ..., [2008,7,12,...]]
    '''
    openFile = open(fileName)
    allData = []
    for line in openFile:
        yearData = []
        yearDataAsStrings = line.split(',')
        for item in yearDataAsStrings:
            yearData.append(int(item))
        allData.append(yearData)
        
    openFile.close()
    return allData

def main(args):
    if len(args) != 2:
        print 'usage: python %s weather_file' % args[0]
        sys.exit()
        
    filename = args[1]
    
    data = loadWeatherData(filename)
    
    # The way I'm keeping track of maximums and minimums is to first set the
    # value as `None` then use `or highestMean == None` in my comparisons
    
    highestMean = None
    highestMeanYear = None
    
    lowestMean = None
    lowestMeanYear = None
    
    highestStdDev = None
    highestStdDevYear = None
    
    lowestStdDev = None
    lowestStdDevYear = None
    
    highestTemp = None
    highestTempYear = None
    
    lowestTemp = None
    lowestTempYear = None
    
    print "High temperature data (Fahrenheit)"
    print
    print "Year      Mean   Std Dev"
    for yearData in data:
        year = yearData[0]
        temps = yearData[1:]
        theMean = mean(temps)
        stdDev = standardDeviation(temps)
        highest = max(temps)
        lowest = min(temps)
        
        print "%s%10.2f%10.2f" % (year, theMean, stdDev)
        
        if theMean > highestMean or highestMean == None:
            highestMean = theMean
            highestMeanYear = year
        
        if theMean < lowestMean or lowestMean == None:
            lowestMean = theMean
            lowestMeanYear = year
        
        if stdDev > highestStdDev or highestStdDev == None:
            highestStdDev = stdDev
            highestStdDevYear = year
        
        if stdDev < lowestStdDev or lowestStdDev == None:
            lowestStdDev = stdDev
            lowestStdDevYear = year
        
        if highest > highestTemp or highestTemp == None:
            highestTemp = highest
            highestTempYear = year
        
        if lowest < lowestTemp or lowestTemp == None:
            lowestTemp = lowest
            lowestTempYear = year
        
    
    print # empty line
    
    print 'Highest mean temperature: %.2f (%s)' % (highestMean, highestMeanYear)
    print 'Lowest mean temperature: %.2f (%s)' % (lowestMean, lowestMeanYear)
    print 'Highest standard deviation: %.2f (%s)' % (highestStdDev, highestStdDevYear)
    print 'Lowest standard deviation: %.2f (%s)' % (lowestStdDev, lowestStdDevYear)
    print 'Highest temperature: %.2f (%s)' % (highestTemp, highestTempYear)
    print 'Lowest temperature: %.2f (%s)' % (lowestTemp, lowestTempYear)


main(sys.argv)