python-mastery/Exercises/soln2_1.md

Exercise 2.1 - Solution

# readrides.py

import csv

def read_rides_as_tuples(filename):
    '''
    Read the bus ride data as a list of tuples
    '''
    records = []
    with open(filename) as f:
        rows = csv.reader(f)
        headings = next(rows)     # Skip headers
        for row in rows:
            route = row[0]
            date = row[1]
            daytype = row[2]
            rides = int(row[3])
            record = (route, date, daytype, rides)
            records.append(record)
    return records

def read_rides_as_dicts(filename):
    '''
    Read the bus ride data as a list of dicts
    '''
    records = []
    with open(filename) as f:
        rows = csv.reader(f)
        headings = next(rows)     # Skip headers
        for row in rows:
            route = row[0]
            date = row[1]
            daytype = row[2]
            rides = int(row[3])
            record = {
                'route': route, 
                'date': date, 
                'daytype': daytype, 
                'rides' : rides
                }
            records.append(record)
    return records

class Row:
    # Uncomment to see effect of slots
    # __slots__ = ('route', 'date', 'daytype', 'rides')
    def __init__(self, route, date, daytype, rides):
        self.route = route
        self.date = date
        self.daytype = daytype
        self.rides = rides

# Uncomment to use a namedtuple instead
#from collections import namedtuple
#Row = namedtuple('Row',('route','date','daytype','rides'))

def read_rides_as_instances(filename):
    '''
    Read the bus ride data as a list of instances
    '''
    records = []
    with open(filename) as f:
        rows = csv.reader(f)
        headings = next(rows)     # Skip headers
        for row in rows:
            route = row[0]
            date = row[1]
            daytype = row[2]
            rides = int(row[3])
            record = Row(route, date, daytype, rides)
            records.append(record)
    return records

if __name__ == '__main__':
    import tracemalloc
    tracemalloc.start()
    read_rides = read_rides_as_tuples # Change to as_dicts, as_instances, etc.
    rides = read_rides("Data/ctabus.csv")

    print('Memory Use: Current %d, Peak %d' % tracemalloc.get_traced_memory())

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