Python Web -L05 (List Comprehension)
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# simply function
old_list = ['this','is','a','man']
new_list = []
for item in old_list:
if len(item) > 2:
new_list.append(item[::-1])
# list comprehension
# new_list = [expression action, for loop, filter]
new_list = [item[::1] for item in old_list if len(item) > 2]
print(new_list)
###################################################
def temp():
new_list = []
for i in range(10):
new_list.append(i**2)
return new_list
# nested for loop, we can copy the for loop order
print(temp())
x = [i**2 for i in range(10)]
print("x value is ",x)
l = []
for i in range(5):
for j in range(5):
for k in range(5):
l.append((i,j,k))
#print(l)
l = [(i,j,k) for i in range(5) for j in range(5) for k in range(5)]
print(l)
l = []
for i in range(5):
for j in range(5):
for k in range(5):
if i == j:
l.append((i,j,k))
l = [(i,j,k) for i in range(5) for j in range(5) for k in range(5) if i == j]
print(l)
# ex 1
l = []
for i in range(1,6):
if i % 2 == 0:
for j in range(1,6):
if j % 3 == 0:
l.append((i,j))
l = [(i,j) for i in range(1,6) if i % 2 == 0 \
for j in range(1,6) if j % 3 == 0] # "\" connect to next line
print(l)
#ex 2
l = []
for i in range(1,6):
for j in range(1,6):
if i % 2 == 0:
if j % 3 == 0:
l.append((i,j))
l = [(i,j) for i in range(1,6) for j in range(1,6) if i % 2 == 0 if j % 3 == 0]
print(l)
#ex 3
#l = []
for i in range(1,6):
for j in range(1,6):
if i % 2 == 0 and j % 3 == 0:
l.append((i,j))
l = [(i,j) for i in range(1,6) for j in range(1,6) if i % 2 == 0 and j % 3 == 0]
print(l)
Python
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