Initial commit

Solutions/2_5/cta.py

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+# cta.py
+
+from collections import defaultdict, Counter
+import tracemalloc
+import readrides
+
+tracemalloc.start()
+
+rows = readrides.read_rides_as_dicts('../../Data/ctabus.csv')
+
+# --------------------------------------------------
+# Question 1:  How many bus routes are in Chicago?
+# Solution: Use a set to get unique values. 
+
+routes = set()
+for row in rows:
+    routes.add(row['route'])
+print(len(routes), 'routes')
+
+# --------------------------------------------------
+# Question 2: How many people rode route 22 on February 2, 2011?
+# Solution: Make dictionary with composite keys
+
+by_route_date = { }
+for row in rows:
+    by_route_date[row['route'], row['date']] = row['rides']
+
+print('Rides on Route 22, February 2, 2011:', by_route_date['22','02/02/2011'])
+
+# --------------------------------------------------
+# Question 3: Total number of rides per route
+# Solution: Use a counter to tabulate things
+rides_per_route = Counter()
+for row in rows:
+    rides_per_route[row['route']] += row['rides']
+
+# Make a table showing the routes and a count ranked by popularity
+for route, count in rides_per_route.most_common():
+    print('%5s %10d' % (route, count))
+
+# --------------------------------------------------
+# Question 4: Routes with greatest increase in ridership 2001 - 2011
+# Solution: Counters embedded inside a defaultdict
+
+rides_by_year = defaultdict(Counter)
+for row in rows:
+    year = row['date'].split('/')[2]
+    rides_by_year[year][row['route']] += row['rides']
+
+diffs = rides_by_year['2011'] - rides_by_year['2001']
+for route, diff in diffs.most_common(5):
+    print(route, diff)
+
+# ---- Memory use
+print('Memory Use: Current %d, Peak %d' % tracemalloc.get_traced_memory())

Solutions/2_5/readrides.py

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+# 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:
+    __slots__ = ('route', 'date', 'daytype', 'rides')
+    def __init__(self, route, date, daytype, rides):
+        self.route = route
+        self.date = date
+        self.daytype = daytype
+        self.rides = 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
+
+# Read as columns
+def read_rides_as_columns(filename):
+    '''
+    Read the bus ride data into 4 lists, representing columns
+    '''
+    routes = []
+    dates = []
+    daytypes = []
+    numrides = []
+    with open(filename) as f:
+        rows = csv.reader(f)
+        headings = next(rows)     # Skip headers
+        for row in rows:
+            routes.append(row[0])
+            dates.append(row[1])
+            daytypes.append(row[2])
+            numrides.append(int(row[3]))
+    return dict(routes=routes, dates=dates, daytypes=daytypes, numrides=numrides)
+
+# The great "fake"
+
+import collections
+class RideData(collections.Sequence):
+    def __init__(self):
+        # Each value is a list with all of the values (a column)
+        self.routes = []
+        self.dates = []
+        self.daytypes = []
+        self.numrides = []
+        
+    def __len__(self):
+        # All lists assumed to have the same length
+        return len(self.routes)
+
+    def append(self, d):
+        self.routes.append(d['route'])
+        self.dates.append(d['date'])
+        self.daytypes.append(d['daytype'])
+        self.numrides.append(d['rides'])
+        
+    def __getitem__(self, index):
+        return { 'route': self.routes[index],
+                 'date': self.dates[index],
+                 'daytype': self.daytypes[index],
+                 'rides': self.numrides[index] }
+
+# Modified version using RideData
+def read_rides_as_dicts(filename):
+    '''
+    Read the bus ride data as a list of dicts
+    '''
+    records = RideData()
+    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
+
+if __name__ == '__main__':
+    import tracemalloc
+    tracemalloc.start()
+    read_rides = read_rides_as_dicts # Change to as_dicts, as_instances, etc.
+    rides = read_rides("../../Data/ctabus.csv")
+
+    print('Memory Use: Current %d, Peak %d' % tracemalloc.get_traced_memory())