Python Error: “ValueError: need more than 1 value to unpack”

Question

I am trying to learn how to code in Python, whenever I do a exercise involving from sys import argv I get this error code:

Traceback (most recent call last): File "C:/Users/Kaleb/PycharmProjects/python ex13.py", line 3, in script, first, second, third = argv ValueError: need more than 1 value to unpack

This is the code im trying to do:

from sys import argv

script, first, second, third = argv

print "The script is called:", script
print "Your first variable is:", first
print "Your second variable is:", second
print "Your third variable is:", third

I am not sure why it is doing this and im very new to coding. I had had a look around but I cannot find anything helpful or that I can understand.

What does this error mean and what do I need to do to fix it?

I asked how you _run the script_, as in, `C:\Users\Kaleb> py myscript.py 1 2 3`. — TigerhawkT3, Dec 20 '15 at 01:20
What do you mean, "nope"? You didn't pass three arguments? Can you tell us how you _did_ run it, then? The exercise should have discussed this; it's kind of the whole point of it. — TigerhawkT3, Dec 20 '15 at 01:23
Possible duplicate of [Python Error: "ValueError: need more than 1 value to unpack"](http://stackoverflow.com/questions/2814128/python-error-valueerror-need-more-than-1-value-to-unpack) — Kevin Brown-Silva, Dec 20 '15 at 01:29
If you don't even understand the troubleshooting questions, that means you should actually read the exercises, not just copy and paste the code into a .py file. — TigerhawkT3, Dec 20 '15 at 01:32
My problem was i was not calling the script correctly thanks if you helped me — Kaleb Tempest, Dec 20 '15 at 01:33

score 1 · Answer 1 · answered Dec 20 '15 at 01:19

You're trying to assign variables to non-existent values

script, first, second, third = argv

When you call your script you need to pass in three parameters as well

So you can call your script like this:

python ex13.py test1 test2 test3

You should see:

The script is called: ./ex13.py                                                                            
Your first variable is: test1                                                                               
Your second variable is: test2                                                                              
Your third variable is: test3

score 0 · Accepted Answer · answered Dec 20 '15 at 01:20

It works perfectly fine if you call it correctly. Assuming you script is called output.py you need to run it like this:

python output.py z u i

where z, u and i are three arguments which you try to unpack. Then you receive:

The script is called: output.py
Your first variable is: z
Your second variable is: u
Your third variable is: i

If you call it without these three arguments just using

python output.py

you receive the error message you mentioned:

Traceback (most recent call last):
  File "output.py", line 3, in <module>
    script, first, second, third = argv
ValueError: need more than 1 value to unpack

Python Error: “ValueError: need more than 1 value to unpack”

2 Answers2