New problems

Author: Guilherme Diego

cap1/.problem4.py.swp

@@ -0,0 +1,23 @@
+from operator import attrgetter
+
+class User:
+    def __init__(self, user_id):
+        self.user_id = user_id
+
+    def __repr__(self):
+        return 'User({})'.format(self.user_id)
+
+users = [User(23), User(3), User(99)]
+
+def sort_users():
+    return sorted(users, key=lambda u: u.user_id)
+
+def sort_users_w_attrgetter():
+    return sorted(users, key=attrgetter('user_id'))
+
+def exec():
+    print(sort_users())
+    print(sort_users_w_attrgetter())
+
+if __name__ == '__main__':
+    exec()

cap1/problem14.py

@@ -0,0 +1,34 @@
+from itertools import groupby
+from operator import itemgetter
+from collections import defaultdict
+rows = [
+    {'address': '5412 N CLARK', 'date': '07/01/2012'},                
+    {'address': '5148 N CLARK', 'date': '07/04/2012'},               
+    {'address': '5800 E 58TH', 'date': '07/02/2012'},                
+    {'address': '2122 N CLARK', 'date': '07/03/2012'},                
+    {'address': '5645 N RAVENSWOOD', 'date': '07/02/2012'},                
+    {'address': '1060 W ADDISON', 'date': '07/02/2012'},                
+    {'address': '4801 N BROADWAY', 'date': '07/01/2012'},                
+    {'address': '1039 W GRANVILLE', 'date': '07/04/2012'},                
+]
+
+def way_1():
+    rows.sort(key=itemgetter('date'))
+    
+    for date, items in groupby(rows, key=itemgetter('date')):
+        print(date)
+        for i in items:
+            print('    ', i)
+    
+def way_2():
+    rows_by_date = defaultdict(list)
+
+    for row in rows:
+        rows_by_date[row['date']].append(row)
+
+    for r in rows_by_date['07/01/2012']:
+        print(r)
+
+if __name__ == '__main__':
+    # way_1()
+    way_2()

cap1/problem15.py

@@ -0,0 +1,49 @@
+import time
+
+rows = [1, 4, -5, 10, -7, 2, 3, -1]
+
+def list_comprehesion():
+    rows_filtered_positive = [r for r in rows if r >= 0]
+    rows_filtered_negative = [r for r in rows if r < 0]
+
+    print(rows_filtered_positive)
+    print(rows_filtered_negative)
+
+def generator():
+    rows_filtered_positive = (r for r in rows if r >= 0)
+    rows_filtered_negative = (r for r in rows if r < 0)
+
+    for row in rows_filtered_positive:
+        print(row)
+
+    for row in rows_filtered_negative:
+        print(row)
+
+def filter_try_except():
+    values = '1 2 -3 - 4 N/A'.split()
+    def is_int(n):
+        try:
+            x = int(n)
+            return True
+        except:
+            return False
+
+    vals = list(filter(is_int, values))
+    print(vals)
+
+
+if __name__ == '__main__':
+    print('List Comprehesion')
+    t1 = time.time()
+    list_comprehesion()
+    print('spent: %.6f' % (time.time() - t1))
+
+    print('Generator')
+    t1 = time.time()
+    generator()
+    print('spent: %.6f' % (time.time() - t1))
+
+    print('Filter try/except')
+    t1 = time.time()
+    filter_try_except()
+    print('spent: %.6f' % (time.time() - t1))