I'm running the code below in Spyder.
I have typed it in a py file and simply hit the run button.
When I try to run it I get the error:
ValueError: need more than 1 value to unpack
As shown here you are meant to give the inputs for the argv variable before running the program but I don't know how to do this is spyder?
http://learnpythonthehardway.org/book/ex13.html
from sys import argv
script, first, second, third = argv
print "The script is called:", script
print "The first variable is:", first
print "The second variable is:", second
print "Your third variable is:", third
To pass argv to a script in Spyder, you need to go the menu entry
Run > Configuration per file
or press the Ctrl+F6 key, then look for the option called
Command line options
on the dialog that appears after that, and finally enter the command line arguments you want to pass to the script, which in this case could be
one two three
In addition to configuring in the Run->Configure as explained in other answers,
you can use "runfile" directly from the console.
Run the following:
runfile('ex13.py', args='first second third')
In Spyder, go Run > Configure and define your argv values as showing in following diagram and to run the script just press F6
Read the FAQ at the bottom of the page, it specifically mentions this error.
Common Student Questions
Q. When I run it I get ValueError: need more than 1 value to unpack.
Remember that an important skill is paying attention to details. If you look at the What You Should See section you see that I run the script with parameters on the command line. You should replicate how I ran it exactly.
Make sure you run the command:
$ python ex13.py first 2nd 3rd
>> The script is called: ex13.py
>> Your first variable is: first
>> Your second variable is: 2nd
>> Your third variable is: 3rd
You can ensure that the arguments are supplied.
if __name__ == '__main__':
if len(argv) == 4:
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
else:
print 'You forgot the args...'
Related
I'm trying to learn python by following book Named "learn python3 by hard way"
They gave this example of code.
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)
But in VS code pylint giving me this error.
Possible unbalanced tuple unpacking with sequence: left side has 4 label(s), right side has 0 value(s)
Book writer hadn't explained this and I want to know what does this error means
But they also said
Run the program like this (and you must pass three command line
arguments):
$ python3.6 ex13.py first 2nd 3rd
And how often python programmers use this method in practical world and any example of use-case.
The argument may not exactly be four. If it is less or more than 4, it may raise ValueError
I am getting valueError in this code.
I do not know why?
from sys import argv
(script,first,second,third)=argv
print('The script is called:',script)
print('The first variable is :',first)
print('The second variable is :',second)
print('The third variable is :',third)
You're either not providing enough arguments to run your script or providing too many arguments, you need to provide three arguments like this:
python3 script.py first second third
I'm practicing Python with the book called Learn "Python The Hard Way 3rd edition". I searched that this book is a good resource to get a start.
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)
And I got an error saying that value error: not enough values to unpack (expected 4, got 1).
You need to run the script with three arguments, so that argv contains four elements (the first is the script's name).
argv is a list containing the following:
argv[0] is the script pathname if known
argv[1], argv[2], argv[3]... contains arguments passed from the shell.
In order for your code to work you need to run it with 3 arguments so that they can be unpacked and assigned to your 4 variables.
The error is at script, first, second, third = argv. I would like to understand why I am getting the error and how to fix it.
from sys import argv
script, first, second, third = argv
print("The script is called: ", script)
print("The first variable is: ", first)
print("The second variable is: ", second)
print("The third variable is: ", third)
Run it from the shell like this:
python script.py arg1 arg2 arg3
argv variable contains command line arguments. In your code you expected 4 arguments, but got only 1 (first argument always script name). You could configure arguments in pycharm. Go to Run -> Edit Configurations. Then create a new python configuration. And there you could specify Script parameters field. Or you could run your script from command line as mentioned by dnit13.
You could run it like this: python script.py first, second, third
I think you are running the following command:
python script.py
You are writing a program which is aksing for 4 inputs and you are giving onle one. That's why you are receiving an error. You can use the below command:
python script.py Hello How Are
how can I execute Python 3.3 script in Spyder console, and that has variables?
My sample code (C:/test/myfile.py) is
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 have tried exec(open("C:\test\myfile.py").read()) - and the error I get is "ValueError: need more than 1 value to unpack. I want to supply the variables first = "1st", second = "2nd", third = "3rd". How can I write the exec() so that it can handle the inputs?
I'm using Python 3.3, 64-bit installation, Windows OS, installation: WinPython.
You need to go
Run > Configuration per file
(or hit Ctrl+F6) and in the dialog that it appears you need to check
Command line options
and write (for example) there
1 2 3
After closing this dialog and hitting F5, you'll see the output you are expecting.
Note: Please remember that these command line options are saved between Spyder restarts as part of the file run config, so if you want to change them, you need to hit Ctrl+F6 again.
What also works is the IPython console of Spyder is:
In [1]: runfile('C:/yourfolder/myfile.py',args='one two three')