Python | Did You Know? For Loop Takes 3x More Time than List Comprehension

Did you know this fact about Python?
For Loop Takes 3x More Time than List Comprehension and Range is 2x more effective than List Comprehension

Let me show you with an example:

For loop + append

def method1():
l=[]
for i in range(10000):
l.append(i)
return l

For loop + addition

def method2():
l=[]
for i in range(10000):
l+=[i]
return l

List Comprehension + For loop

def method3():
l=[i for i in range(10000)]
return l

Range + List

def method4():
l=list(range(10000))
return l

Now let's look at which functions take how long:

%timeit method1() #For loop + append
1000 loops, best of 3: 1300 µs per loop
%timeit method2() #For loop + addition
1000 loops, best of 3: 1270 µs per loop
%timeit method3() #List Comprehension
1000 loops, best of 3: 583 µs per loop
%timeit method4() #Range + List
10000 loops, best of 3: 258 µs per loop

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