CODEWITHSUNDEEP
python
user3074142
user3074142

Reputation: 11

Why ValueError: Need more than 1 value to unpack

I know others have asked about this error, but I'm not sure why I keep getting this error for this code. I'm writing a code to open and read a textfile, then replace each letter in it with a new letter. The letters and their replacements are specified in my dictionary "replacements."

This is my code right now:

def decode(text):
    replacements={'a':'L','b':'A','c':'O','d':'Z','e':'M','f':'V','g':'R','h':'B','i':'U','j':'S','k':'Q','l':'K','m':'Y','n':'J','o':'W','p':'H','q':'E','r':'X','s':'T','t':'P','u':'F','v':'I','w':'G','x':'C','y':'D','z':'N'}
    infile=open(text).read()
    outfile=open("output.txt",'w')
    for letter in infile:
        for old,new in replacements:
            newtext=infile.replace(old,new)
            outfile.write(newtext)
    infile.close()

When I run the code, the error message comes up for the line "for old,new in replacements" and tells me it needs more than 1 value to unpack. I'm very new to programming .. can someone please explain why I'm getting this error?

Upvotes: 1

Views: 573

Answers (2)

Ray
Ray

Reputation: 2510

I think Jakob's answer solved the problem but I would like to rearrange the code a little bit.

def decode(text):
    replacements={'a':'L','b':'A','c':'O','d':'Z','e':'M','f':'V','g':'R','h':'B','i':'U','j':'S','k':'Q','l':'K','m':'Y','n':'J','o':'W','p':'H','q':'E','r':'X','s':'T','t':'P','u':'F','v':'I','w':'G','x':'C','y':'D','z':'N'}
    with open(text, 'r') as infile:
        instr = infile.read()
        for old,new in replacements.iteritems():
            instr = instr.replace(old, new)    
        with open("output.txt", 'w') as outfile:
            outfile.write(instr)

  1. Doing replacement doesn't require looping through all the letters. It will find convert all matches.

  2. It is easier to use with open, since it will take care of close automatically.

Hope these suggestions help you learn Python.

Upvotes: 0

Jakob Bowyer
Jakob Bowyer

Reputation: 34688

 for old,new in replacements:

Will iter the keys in a dict.

 for old,new in replacements.iteritems():

Will iterate the key and value in the dict

Upvotes: 5

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