Chapter 3 done.

altvec · altvec · commit 5835b01fca38 · 2020-06-28T19:24:59.000+05:00
diff --git a/Work/fileparse.py b/Work/fileparse.py
@@ -6,7 +6,7 @@
 
 
 def parse_csv(
-    filename,
+    lines,
     select=None,
     types=None,
     has_headers=True,
@@ -19,29 +19,28 @@ def parse_csv(
     if select and not has_headers:
         raise RuntimeError("Select argument requires column headers")
 
-    with open(filename) as f:
-        rows = csv.reader(f, delimiter=delimiter)
-        headers = next(rows) if has_headers else []
+    rows = csv.reader(lines, delimiter=delimiter)
+    headers = next(rows) if has_headers else []
+    if select:
+        indices = [headers.index(colname) for colname in select]
+        headers = select
+    records = []
+    for idx, row in enumerate(rows, start=1):
+        if not row:
+            continue
         if select:
-            indices = [headers.index(colname) for colname in select]
-            headers = select
-        records = []
-        for idx, row in enumerate(rows, start=1):
-            if not row:
+            row = [row[index] for index in indices]
+        if types:
+            try:
+                row = [func(val) for func, val in zip(types, row)]
+            except ValueError as e:
+                if not silence_errors:
+                    print(f'Row {idx}: Couldn\'t convert {row}')
+                    print(f'Row {idx}: Reason {e}')
                 continue
-            if select:
-                row = [row[index] for index in indices]
-            if types:
-                try:
-                    row = [func(val) for func, val in zip(types, row)]
-                except ValueError as e:
-                    if not silence_errors:
-                        print(f'Row {idx}: Couldn\'t convert {row}')
-                        print(f'Row {idx}: Reason {e}')
-                    continue
-            if headers:
-                record = dict(zip(headers, row))
-            else:
-                record = tuple(row)
-            records.append(record)
+        if headers:
+            record = dict(zip(headers, row))
+        else:
+            record = tuple(row)
+        records.append(record)
     return records
diff --git a/Work/pcost.py b/Work/pcost.py
@@ -1,31 +1,24 @@
+#!/usr/bin/env python3
+
 # pcost.py
 #
 # Exercise 1.27
-import sys
-import csv
+from report import read_portfolio
 
 
 def portfolio_cost(filename):
     '''Return portfolio cost.'''
-    total_cost = 0.0
-    with open(filename, 'rt') as file:
-        rows = csv.reader(file)
-        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
-            except ValueError:
-                print(f'Row {rowno}: Bad row: {row}')
-    return total_cost
+    portfolio = read_portfolio(filename)
+    return sum([s['shares'] * s['price'] for s in portfolio])
+
 
+def main(args):
+    if len(args) != 2:
+        raise SystemExit(f'Usage: {args[0]} portfolio_file')
+    cost = portfolio_cost(args[1])
+    print(f'Total cost: {cost}')
 
-if len(sys.argv) == 2:
-    filename = sys.argv[1]
-else:
-    filename = '../Work/Data/portfolio.csv'
 
-cost = portfolio_cost(filename)
-print(f'Total cost: {cost}')
+if __name__ == '__main__':
+    import sys
+    main(sys.argv)
diff --git a/Work/report.py b/Work/report.py
@@ -1,39 +1,30 @@
+#!/usr/bin/env python3
+
 # report.py
 #
 # Exercise 2.4
-import csv
+from fileparse import parse_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, 'rt') as f:
-        rows = csv.reader(f)
-        headers = next(rows)
-        for row in rows:
-            record = dict(zip(headers, row))
-            portfolio.append({
-                'name': record['name'],
-                'shares': int(record['shares']),
-                'price': float(record['price']),
-            })
-    return portfolio
+    with open(filename) as lines:
+        return parse_csv(
+            lines,
+            select=['name', 'shares', 'price'],
+            types=[str, int, float],
+        )
 
 
 def read_prices(filename):
     '''
     Read a CSV file of price data into a dict mapping names to prices.
     '''
-    prices = {}
-    with open(filename, 'rt') as f:
-        rows = csv.reader(f)
-        for row in rows:
-            if row:
-                prices[row[0]] = float(row[1])
-    return prices
+    with open(filename) as lines:
+        return dict(parse_csv(lines, types=[str, float], has_headers=False))
 
 
 def make_report(portfolio, prices):
@@ -68,4 +59,11 @@ def portfolio_report(portfolio_file, prices_file):
     print_report(report)
 
 
-portfolio_report('Data/portfolio.csv', 'Data/prices.csv')
+def main(args):
+    if len(args) != 3:
+        raise SystemExit(f'Usage: {args[0]} portfolio_file prices_file')
+    portfolio_report(args[1], args[2])
+
+if __name__ == '__main__':
+    import sys
+    main(sys.argv)
