reader for ex 2.6

reader.py

@@ -0,0 +1,54 @@
+import collections.abc
+import csv
+
+
+class DataCollection(collections.abc.Sequence):
+    def __init__(self, headers):
+        self.headers = headers
+        self.data = dict()
+        for name in headers:
+            self.data[name] = []
+
+    def __len__(self):
+        return len(self.data[self.headers[0]])
+
+    def __getitem__(self, index):
+        if isinstance(index, slice):
+            value = DataCollection(self.headers)
+        else:
+            value = {}
+
+        for name in self.headers:
+            if isinstance(index, slice):
+                value.data[name] = self.data[name][index]
+            else:
+                value[name] = self.data[name][index]
+        return value
+
+    def append(self, d):
+        for name in self.headers:
+            self.data[name].append(d[name])
+
+
+def read_csv_as_dicts(filename, conversions):
+    value = []
+    with open(filename) as f:
+        rows = csv.reader(f)
+        headers = next(rows)
+        for row in rows:
+            value.append(
+                {name: func(val)
+                 for name, func, val in zip(headers, conversions, row)})
+    return value
+
+
+def read_csv_as_columns(filename, conversions):
+    with open(filename) as f:
+        rows = csv.reader(f)
+        headers = next(rows)
+        value = DataCollection(headers)
+        for row in rows:
+            value.append(
+                {name: func(val)
+                 for name, func, val in zip(headers, conversions, row)})
+    return value