Python array spread

As Alexander points out in the comments, list addition is concatenation.

a = [1,2,3,4]
b = [10] + a  # N.B. that this is NOT `10 + a`
# [10, 1, 2, 3, 4]
You can also use list.extend

a = [1,2,3,4]
b = [10]
b.extend(a)
# b is [10, 1, 2, 3, 4]
and newer versions of Python allow you to (ab)use the splat (*) operator.

b = [10, *a]
# [10, 1, 2, 3, 4]
Your choice may reflect a need to mutate (or not mutate) an existing list, though.

a = [1,2,3,4]
b = [10]
DONTCHANGE = b

b = b + a  # (or b += a)
# DONTCHANGE stays [10]
# b is assigned to the new list [10, 1, 2, 3, 4]

b = [*b, *a]
# same as above

b.extend(a)
# DONTCHANGE is now [10, 1, 2, 3, 4]! Uh oh!
# b is too, of course...

Source: stackoverflow.com

Similar codes

2 votes166 views1 answer
How to receive password using tkinter entry
Python
0 vote174 views1 answer
Shutil cut poython
Python
3 votes202 views1 answer
ModuleNotFoundError: No module named 'django.core.urlresolvers'
Python Django
91 votes180 views6 answers
Time.sleep
Python
0 vote199 views1 answer
Huesos del cuerpo humano
Python
0 vote171 views1 answer
Getting multiple of 5 python
Python
17 votes173 views4 answers
Bubble sort python
Python
-1 vote172 views1 answer
Py string find regex pos
Python
79 votes155 views3 answers
Reverse element in a list in python 3
Python
0 vote174 views1 answer
Carnage
Python