List Comprehension

Beginning Python Programming

Makzan, 2020 April.

Example: for-loop approach

L = range(1,10)
for x in L:
  print(x*x)

L = range(1,10)
L2 = []
for x in L:
  L2.append( x*x )
print(L2)

L2 = [x*x for x in range(1,10)]
print(L2)

L2 = [x*x for x in range(1,10)]

L2 = []
for x in range(1,10):
  L2.append( x*x )
print(L2)

1. Construct a new list

2. The list source is an iteration

3. Each new element is calculated from the source element.

4. Result list

scores = [34, 65, 45, 67, 78, 56, 80]
passed_scores = [x for x in scores if x >= 60]
print(passed_scores)

# Result:
# [65, 67, 78, 80]

scores = [34, 65, 45, 67, 78, 56, 80]
L = [x for x in scores if x >= 60]

L = []
for x in scores:
  if x >= 60:
    L.append(x)

1. Construct a new list

2. The list source is an iteration

4. Each new element is calculated from the source element.

5. Result list

3. Add to the list according to condition


scores = [34, 65, 45, 67, 78, 56, 80]
L = [x for x in scores if x >= 60]

By makzan