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Name: [002] Ian Ozsvald
Member: 105 months
Authored: 181 videos
Description: I am the co-founder of ShowMeDo (see http://showmedo.com/about), author of `The Screencasting Handbook <http://thescreencastinghandbook.com>`_ and the founder of the professional screencast production company `ProCasts <http://procasts.co.uk>`_: .. image:: http://procasts.co.uk/media/procasts_sma ...

Solution to the unit-test task for average [ID:255] (14/17)

in series: Python 101 - easygui and csv

(Showmedo is undergoing major changes. To report any problems viewing the videos please email us and include browser and OS specifics. Cheers - Kyran.)

Adding the unit-test for our average function takes just a few lines of code, here you can see my solution to the task that I set in the previous episode. We also look at the addition of the 'measured2' list and associated code which will calculate the average for the 2nd column of data.

Created May 2007, running time 1 minute

# Two files here

#
# 910130_csvReader.py
#
import csv
import sys
import easygui

def getFileAndPath():
    "Get fully-qualified path to the csv file"
    fileAndPath = easygui.fileopenbox(title="Select .CSV file")
    print "Using:",fileAndPath 
    return fileAndPath

def getLinesInCSVFile(fileAndPath):
    "read lines in CSV file, return a list of these lines"
    linesInCSV = []
    reader = csv.reader(open(fileAndPath, "rb"))
    for row in reader:
        linesInCSV.append(row)
    return linesInCSV

def justNumbers(listOfStrings):
    "True if the list contains just numbers represented as strings"
    # e.g. ['22.4', '23.9']
    isJustNumbers = True
    for item in listOfStrings:        
        try:
            nbr = float(item)            
        except ValueError:
            isJustNumbers = False
    return isJustNumbers

def getNumbers(listOfStrings):
    "Convert a list of strings-of-numbers to a list of numbers, e.g. ['22.4', '23.9'] -> [22.4, 23.9]"
    numbers = []
    for item in listOfStrings:
        nbr = float(item)            
        numbers.append(nbr)
    return numbers

def average(values):
    """Computes the arithmetic mean of a list of numbers"""
    return sum(values, 0.0) / len(values)

if __name__ == "__main__":
    # get the file-name
    #fileAndPath = getFileAndPath()
    # NOTE quick hack to make our test/development process quicker
    fileAndPath = "C:/LearningPython_CSV/measured.csv"
    print fileAndPath
        
    # read the CSV file
    linesInCSV = getLinesInCSVFile(fileAndPath)
    print linesInCSV
        
    # print out the headings and the contents
    print
    print "Headings:",linesInCSV[0]
    measured1 = []
    measured2 = []
    for n in range(1,4):
        line = linesInCSV[n]
        isJustNumbers = justNumbers(line)
        if not isJustNumbers:
            print "ERROR!  Expected a line of numbers, instead we got:",line
            sys.exit() 
        # we only get here if justNumbers reports that we only have numbers
        # so we can extract the list of floating-point numbers
        numbers = getNumbers(line)
        #print numbers
        measured1.append(numbers[0])
        print measured1        
        measured2.append(numbers[1])
        print measured2
    averaged1 = average(measured1)
    print averaged1
    averaged2 = average(measured2)
    print averaged2

#
# 910130_testCsvReader.py
#
import csvReader

def testJustNumbersOnNumbers():
    listOfStrings = ['22.4', '23.9']
    assert csvReader.justNumbers(listOfStrings)
    
def testJustNumbersOnBadNumbers():
    listOfStrings = ['abc', '23.9']
    assert csvReader.justNumbers(listOfStrings) == False

def testGetNumbers():
    listOfStrings = ['22.4', '23.9']
    assert csvReader.getNumbers(listOfStrings) == [22.4, 23.9]

def testAverage():
    assert csvReader.average([1,2,3]) == 2.0
    

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  • Published: 88 months ago

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Mine was slighly different, but similar results.


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