[PYTHON] Comprehension notation

List comprehension

l = []
for i in range(10):
    if i % 2 == 0:
        l.append(i)
print(l)

The same thing is as follows in list comprehension notation

l = [i for i in range(10) if i % 2 ==0]
print(l)

output

[0, 2, 4, 6, 8]

Dictionary comprehension

w = ['Monday', 'Tuesday','Friday']
f = ['banana', 'apple', 'orange']
d= {}
for x, y in zip(w,f):
    d[x]=y
print(d)

The same thing is as follows in the dictionary comprehension

w = ['Monday', 'Tuesday','Friday']
f = ['banana', 'apple', 'orange']
d = {x:y for x,y in zip(w,f)}
print(d)

output

{'Monday': 'banana', 'Tuesday': 'apple', 'Friday': 'orange'}

Set comprehension

s = set()
for i in range(10):
    if i % 2 == 0:
        s.add(i)
print(s)

The same thing is as follows in the set comprehension notation

s = {i for i in range(10) if i % 2 == 0}
print(s)

output

{0, 2, 4, 6, 8}

Generator type

def g():
    for i in range(10):
        if i % 2 == 0:
            yield i
g = g()
print(next(g))
print(next(g))
print(next(g))
print(next(g))

The same thing happens in the generator formula as follows.

g = (i for i in range(10) if i % 2 == 0)
print(next(g))
print(next(g))
print(next(g))
print(next(g))

output

0
2
4
6

In addition, the official document says "generator notation", not "generator comprehension". https://docs.python.org/ja/3/reference/expressions.html#generator-expressions

A generator expression is a compact generator notation with parentheses: The generator expression gives a new generator object. This syntax is similar to the comprehension, but is enclosed in parentheses instead of square brackets or curly braces.