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Python: Counter arithmetic and set operations

Python Collections: Exercise-16 with Solution

Write a Python program to perform Counter arithmetic and set operations for aggregating results.

Sample Solution:

Python Code:

import collections
c1 = collections.Counter([1, 2, 3, 4, 5])
c2 = collections.Counter([4, 5, 6, 7, 8])
print('C1:', c1)
print('C2:', c2)
print('\nCombined counts:')
print(c1 + c2)
print('\nSubtraction:')
print(c1 - c2)
print('\nIntersection (taking positive minimums):')
print(c1 & c2)
print('\nUnion (taking maximums):')
print(c1 | c2)

Sample Output:

C1: Counter({1: 1, 2: 1, 3: 1, 4: 1, 5: 1})
C2: Counter({4: 1, 5: 1, 6: 1, 7: 1, 8: 1})

Combined counts:
Counter({4: 2, 5: 2, 1: 1, 2: 1, 3: 1, 6: 1, 7: 1, 8: 1})

Subtraction:
Counter({1: 1, 2: 1, 3: 1})

Intersection (taking positive minimums):
Counter({4: 1, 5: 1})

Union (taking maximums):
Counter({1: 1, 2: 1, 3: 1, 4: 1, 5: 1, 6: 1, 7: 1, 8: 1})

Flowchart:

Python Collections: Counter arithmetic and set operations.

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Python: Tips of the Day

Creates a dictionary with the same keys as the provided dictionary and values generated by running the provided function for each value:

Example:

def tips_map_values(obj, fn):
  ret = {}
  for key in obj.keys():
    ret[key] = fn(obj[key])
  return ret
users = {
  'Owen': { 'user': 'Owen', 'age': 29 },
  'Eddie': { 'user': 'Eddie', 'age': 15 }
}

print(tips_map_values(users, lambda u : u['age'])) # {'Owen': 29, 'Eddie': 15}

Output:

{'Owen': 29, 'Eddie': 15}