Initial commit

Solutions/2_6/colreader.py

@@ -0,0 +1,37 @@
+# colreader.py
+
+import collections
+import csv
+
+class DataCollection(collections.Sequence):
+    def __init__(self, columns):
+        self.column_names = list(columns)
+        self.column_data = list(columns.values())
+
+    def __len__(self):
+        return len(self.column_data[0])
+
+    def __getitem__(self, index):
+        return dict(zip(self.column_names,
+                        (col[index] for col in self.column_data)))
+
+
+def read_csv_as_columns(filename, types):
+    columns = collections.defaultdict(list)
+    with open(filename) as f:
+        rows = csv.reader(f)
+        headers = next(rows)
+        for row in rows:
+            for name, func, val in zip(headers, types, row):
+                columns[name].append(func(val))
+            
+    return DataCollection(columns)
+
+if __name__ == '__main__':
+    import tracemalloc
+    from sys import intern
+
+    tracemalloc.start()
+    data = read_csv_as_columns('../../Data/ctabus.csv', [intern, intern, intern, int])
+    print(tracemalloc.get_traced_memory())
+