Added solution code

Solutions/2_16/pcost.py

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+# pcost.py
+
+import csv
+def portfolio_cost(filename):
+    '''
+    Computes the total cost (shares*price) of a portfolio file
+    '''
+    total_cost = 0.0
+
+    with open(filename) as f:
+        rows = csv.reader(f)
+        headers = next(rows)
+        for rowno, row in enumerate(rows, start=1):
+            record = dict(zip(headers, row))
+            try:
+                nshares = int(record['shares'])
+                price = float(record['price'])
+                total_cost += nshares * price
+            # This catches errors in int() and float() conversions above
+            except ValueError:
+                print(f'Row {rowno}: Bad row: {row}')
+
+    return total_cost
+
+import sys
+if len(sys.argv) == 2:
+    filename = sys.argv[1]
+else:
+    filename = input('Enter a filename:')
+
+cost = portfolio_cost(filename)
+print('Total cost:', cost)

Solutions/2_16/report.py

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+# report.py
+import csv
+
+def read_portfolio(filename):
+    '''
+    Read a stock portfolio file into a list of dictionaries with keys
+    name, shares, and price.
+    '''
+    portfolio = []
+    with open(filename) as f:
+        rows = csv.reader(f)
+        headers = next(rows)
+
+        for row in rows:
+            record = dict(zip(headers, row))
+            stock = {
+                 'name'   : record['name'],
+                 'shares' : int(record['shares']),
+                 'price'   : float(record['price'])
+            }
+            portfolio.append(stock)
+
+    return portfolio
+
+def read_prices(filename):
+    '''
+    Read a CSV file of price data into a dict mapping names to prices.
+    '''
+    prices = {}
+    with open(filename) as f:
+        rows = csv.reader(f)
+        for row in rows:
+            try:
+                prices[row[0]] = float(row[1])
+            except IndexError:
+                pass
+
+    return prices
+
+def make_report_data(portfolio, prices):
+    '''
+    Make a list of (name, shares, price, change) tuples given a portfolio list
+    and prices dictionary.
+    '''
+    rows = []
+    for stock in portfolio:
+        current_price = prices[stock['name']]
+        change        = current_price - stock['price']
+        summary       = (stock['name'], stock['shares'], current_price, change)
+        rows.append(summary)
+    return rows
+        
+# Read data files and create the report data        
+
+portfolio = read_portfolio('../../Work/Data/portfolio.csv')
+prices    = read_prices('../../Work/Data/prices.csv')
+
+# Generate the report data
+
+report    = make_report_data(portfolio, prices)
+
+# Output the report
+headers = ('Name', 'Shares', 'Price', 'Change')
+print('%10s %10s %10s %10s' % headers)
+print(('-' * 10 + ' ') * len(headers))
+for row in report:
+    print('%10s %10d %10.2f %10.2f' % row)