*Memos:
- My post explains a list comprehension, tuple comprehension and set comprehension.
<Dictionary(Dict) Comprehension>
1D dictionary:
v = {x:x**2 for x in range(6)}
print(v) # {0: 0, 1: 1, 2: 4, 3: 9, 4: 16, 5: 25}
*The below is without a dictionary comprehension.
v = {}
for x in range(6):
v.update({x:x**2})
print(v) # {0: 0, 1: 1, 2: 4, 3: 9, 4: 16, 5: 25}
2D dictionary:
*Memos:
- A key can have a tuple, but not a list, set and dictionary.
sample = ((0, 1, 2), (3, 4, 5))
v = {x: {y:y**2 for y in x} for x in sample}
print(v)
# {(0, 1, 2): {0: 0, 1: 1, 2: 4}, (3, 4, 5): {3: 9, 4: 16, 5: 25}}
*The below is without a dictionary comprehension.
sample = ((0, 1, 2), (3, 4, 5))
v = {}
for x in sample:
v.update({x:{}})
for y in x:
v[x].update({y:y**2})
print(v) # {0: 0, 1: 1, 2: 4, 3: 9, 4: 16}
# {(0, 1, 2): {0: 0, 1: 1, 2: 4}, (3, 4, 5): {3: 9, 4: 16, 5: 25}}
<Generator Comprehension>
*Memos:
- Basically, generator comprehension needs
()but it can be passed to a function without().
1D generator:
v = (x**2 for x in range(6))
print(v)
# <generator object <genexpr> at 0x000001C1CBA37440>
print(next(v), next(v), next(v), next(v), next(v), next(v))
# 0 1 4 9 16 25
*The below is without a generator comprehension.
def func():
for x in range(6):
yield x**2
v = func()
print(v)
# <generator object func at 0x000001C1CB737A00>
print(next(v), next(v), next(v), next(v), next(v), next(v))
# 0 1 4 9 16 25
print(x**2 for x in range(6)) # No `()`
# <generator object <genexpr> at 0x000001C1CBA341E0>
v = x**2 for x in range(6) # No `()`
# SyntaxError: invalid syntax
2D generator:
sample = [[0, 1, 2], [3, 4, 5]]
v1 = ((y**2 for y in x) for x in sample)
v2 = next(v1)
v3 = next(v1)
print(v1)
# <generator object <genexpr> at 0x000001C1CBA698A0>
print(v2, v3)
# <generator object <genexpr>.<genexpr> at 0x000001C1CB7BD8A0>
# <generator object <genexpr>.<genexpr> at 0x000001C1CB8D3510>
print(next(v2), next(v2), next(v2), next(v3), next(v3), next(v3))
# 0 1 4 9 16 25
*The below is without a generator comprehension.
def func():
def func(x):
for y in x:
yield y**2
sample = [[0, 1, 2], [3, 4, 5]]
for x in sample:
yield func(x)
v1 = func()
v2 = next(v1)
v3 = next(v1)
print(v1)
# <generator object func at 0x000001C1CB9F44A0>
print(v2, v3)
# <generator object func.<locals>.func at 0x000001C1CBA698A0>
# <generator object func.<locals>.func at 0x000001C1CB7BD8A0>
print(next(v2), next(v2), next(v2), next(v3), next(v3), next(v3))
# 0 1 4 9 16 25