CODEWITHSUNDEEP
python
Sushmita Pal
Sushmita Pal

Reputation: 23

list.append() doesn't add any values to the list

I wanted to open a pdb file and extract its sequence but list.append() does not add any object to my list and displays[ ] as output.I tried doing all the possible alternatives but this doesnot work at atall.

  file=open("c:/pdb/1ana.pdb")
  for lines in file:
      list1=lines.split()
      id=list1[0]
      list=[]
      if id=='ATOM':
          if list1[2]=='C4':
              list.append(list1[3])
 print(list)

Upvotes: 1

Views: 892

Answers (2)

Himanshu dua
Himanshu dua

Reputation: 2523

list=[] is inside for loop which will reset the list in each iteration.

Also, avoid using list as a variable name because list is a keyword in python

Upvotes: 5

matoneski
matoneski

Reputation: 938

It is important to understand how the logic of a loop works. Since you have declared an empty list inside a for loop, each time the iterator (lines in your case) iterates over lines, it resets your appended list to an empty list.

So to avoid this, declare your list variable outside of the for loop and append inside your loop. 

file=open("c:/pdb/1ana.pdb")
list = [] 

for line in file:
list1=lines.split()
    id=list1[0]
    if id=='ATOM':
        if list1[2]=='C4':
            list.append(list1[3])
 print(list)

Cheers.

Upvotes: 0

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