Append method making invalid list

Question

I have an application where i read content from a json file, do some formatting and pass the list for another class.

When i print the first item i see this:

['.docx', '.ppt']

And the second is

['.py', '.java', '.cpp']

I append them to a list, but when i print the list this is the result:

[['.docx', '.ppt'], "['.py', '.java', '.cpp']"]

As this is an invalid list, i cant use for my methods who require a list as parameter.

Answer 1

One of the solution is using extract like :

aList = ['.docx', '.ppt']
blist =['.py', '.java', '.cpp']

aList.extend(blist)
print (aList)

Second one is just using + means :

aList = ['.docx', '.ppt']
blist =['.py', '.java', '.cpp']

aList= aList + blist
print (aList)

Both output :

['.docx', '.ppt', '.py', '.java', '.cpp']

Using extract is more professional

Answer 2

Use extend(). append() adds the list (as a single reference) to the first list. extend() will add its contents:

a = ['.docx', '.ppt']
b = ['.py', '.java', '.cpp']
a.extend(b)
a
# ['.docx', '.ppt', '.py', '.java', '.cpp']