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

9 votes251 views2 answers
Python script to read all file names in a folder
Python
1 vote254 views1 answer
Qlabel alignment center python
Python
4 votes266 views1 answer
What is cleaned data in django
Python
23 votes262 views3 answers
Django drf
Python
1 vote263 views1 answer
Rename coordinate netcdf python xarray
Python
2 votes282 views2 answers
Django regexvalidator example
Python
0 vote272 views1 answer
Matplotlib set y lim
Python
2 votes261 views3 answers
Discord.py clear
Python
-1 vote252 views1 answer
Convert byte to string pytgon
Python
1 vote268 views2 answers
Select columns to include in new dataframe in python
Python