Initial commit

Solutions/2_2/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_2/readport.py

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+# readport.py
+
+import csv
+
+# A function that reads a file into a list of dicts
+def read_portfolio(filename):
+    portfolio = []
+    with open(filename) as f:
+        rows = csv.reader(f)
+        headers = next(rows)
+        for row in rows:
+            record = {
+                'name' : row[0],
+                'shares' : int(row[1]),
+                'price' : float(row[2])
+                }
+            portfolio.append(record)
+    return portfolio

Solutions/2_2/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:
+    # 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())