List and loop

[Sandeep2000]

I am not getting expected output? Why?

phrase="don't panic"
plist=list(phrase)
str1="on tap"
qlist=list(str1)
for item in qlist:
    if item not in plist:
        plist.remove(item)
print(plist)

Output:

Output:
['o', 'n', 't', ' ', 'p', 'a', 'n', 'c']

Desired output:
I want program to remove characters from plist which are not in qlist list.

Output:
['o', 'n', “‘”, 't','p', ‘a’, ‘n’]

[buran]

I am not getting expected output? Why?

define expected output in plain english, please

[woooee]

If you want items in both lists, use set union https://www.programiz.com/python-programming/set#union

[Sandeep2000]

If you want items in both lists, use set union https://www.programiz.com/python-programming/set#union

Thank you for suggesting better ways. I know there are many ways to do this simple task.
But can i expect that output from code above? Can you see if there is something wrong with the code itself.

---

Sorry i misplaced plist and qlist.

phrase="don't panic"
plist=list(phrase)
str1="on tap"
qlist=list(str1)
for item in plist:
    if item not in qlist:
        plist.remove(item)
print(plist)

[Gribouillis]

Can you see if there is something wrong with the code itself.

Yes something is fundamentally wrong in this code: Don't remove items in a python list inside a loop that's iterating on this list. To avoid this, try for item in list(plist), which iterates on a copy of the initial list.

[perfringo]

Main problem with your code is that you mutate the list while iterating over it (it can be done but you must know and understand what are you doing):

"If fact, in any programming language for most part if you mutate something while you iterating over it you living in state of sin and you deserve whatever happens to you" -- Raymond Hettinger, Python core-developer, Transforming Code into Beautiful, Idiomatic Python

If your objective is: 'give me list of all chars in phrase which are in str1' then one can skip all conversions etc and have list comprehension:

>>> phrase="don't panic"
>>> str1="on tap"
>>> [char for char in phrase if char in str1]
['o', 'n', 't', ' ', 'p', 'a', 'n']