python：字典操作，KeyError：'0'

Question

I want to extract information from a text file and store the data in a directionary. The file records semicolon seperated values. That is, it records one property in one line, and the key and the value are seperated by a semicolon followed by a white space.

def info_file_parser(info_file):
  f=open(info_file,'rb')
  info={}
  for line in f:
    line=line.rstrip()
    mlist=line.split(": ")
    if len(mlist)==2:
      info[mlist[0]]=info[mlist[1]]

if __name__='__main__':
  fname="/Users/me/info.txt"
  info_file_parser(fname)

KeyError: '0'. What's wrong with that? Why can't I create keys by assignment?

Answer 1

You are trying to set a key in your dictionary with a key that doesn't exist.

In the if statement of your function, shouldn't it be:

if len(mlist)==2:
      info[mlist[0]]=mlist[1]

Answer 2

this line:

info[mlist[0]]=info[mlist[1]]

tries to store value from info dictonary with key mlist[1] and try this:

info[mlist[0]]=mlist[1]