Introduction to Python

def is_data(line):

    """ Returns true if the line has data

    and false otherwise (header, comments, etc)"""

    answer = True

    if line.startswith('#'):

        # skip comments

        answer = False

    elif line.startswith('D'):

        # skip title row

        answer = False

    else:

        answer = True

    return answer

def count_marlins(data):

    """Receives a line of data and returns the count of Marlins in that line (zero otherwise)"""

    date, species, count = data.split(",")

    marlins = 0

    if species == "marlin":

        marlins = count

    return int(marlins)

# script starts here...

source = open('data.txt', 'r')

number_of_marlins = 0

# count number of data records

for line in source:

    if is_data(line) == True:

        number_of_marlins = number_of_marlins + count_marlins(line)

source.close()

print "Total number of marlins:", number_of_marlins