python - Use Vim Retab to solve TabError: inconsistent use of tabs and spaces in indentation?

Question

Apologize for the newbie question, but I have read the manual, this question, and tried several times without results I expected.

So I was using vim to edit a file (attached). But when running, I got the TabError: inconsistent use of tabs and spaces in indentation error.

Here is what I have tried:

Open the file with Vim. type :retab, and :x. Run the file again. Still got the TabError message.
Open the file again and type :retab! and :x. Run the file again. Still got the TabError message.
Open the file again and type :retab! 4 and :x. Run the file again. This time it works but I have no idea why? Plus, in the files indentation seems excessively long. (I read here that the editor might display 8 spaces for a tab)

My questions are:

What does :retab, :retab!, and :retab! 4 mean?

Why doesn't :retab work on my file?

#!/usr/bin/env python
#Reduce function for computing matrix multiply A*B    
#Input arguments:
#variable n should be set to the inner dimension of the matrix product (i.e., the number of columns of A/rows of B) 
import sys
import string
import numpy

#number of columns of A/rows of B
n = int(sys.argv[1]) 

#Create data structures to hold the current row/column values (if needed; your code goes here)

currentkey = None
alist = [] # list for elelents in  A
blist = [] # list for elements in B
# input comes from STDIN (stream data that goes to the program)
for line in sys.stdin:
    #Remove leading and trailing whitespace
    line = line.strip()
    #Get key/value 
    key, value = line.split('\t',1)
    print(key, value)
    #Parse key/value input (your code goes here)
    key = (key.split(',', 1)[0], key.split(',',1)[1])   
    value = (value.split(',', 1)[0], value.split(',',1)[1], value.split(',',1)[2])  
    #If we are still on the same key...
    if key==currentkey:
        #Process key/value pair (your code goes here)
        # store all values in a lisl
        if value[0]=='A':
        alist.append([value[1], value[2]])
        else:
        blist.append([value[1], value[2]])
        #Otherwise, if this is a new key...
    else:
    #If this is a new key and not the first key we've seen, i.e. currentkey!=None
        if currentkey:
    #compute/output result to STDOUT (your code goes here)
        alist = sorted(alist)
        blist = sorted(blist)
        newlist = [a[1]*b[1] for a,b in zip(alist, blist)]
        res = newlist.sum() 
        print(currentkey, res)
        currentkey = key
        #Process input for new key (your code goes here)

You say you have read the manual, did you type :help retab in Vim? — progmatico
@promatico Thanks for the reply! The manual is a bit technical and I'm not sure I understand it correctly. I guess :retab! 4 means a tab is changed to 4 spaces? If this is the case, why doesn't :retab or :retab!work? — yuqli
See my answer. I think you'll understand after playing with it a bit. — progmatico
They do work. try %:retab! 4 or %:retab 4, but after :set list to see the tabs as tabs. Sometimes they do nothing because there is nothing to be done. — progmatico

progmatico progmatico · Accepted Answer · 2018-02-11T21:33:27

Just type :help retab in Vim and read. I think I can't explain it better than the help. Maybe you are missing the optional range part; use % prefix to apply to the whole file. Also useful is :set list to show you every chars; this will show you the tabs and line ends (disable with :set nolist) and :set <name> with no value to see the current value, ex : set tabstop or followed by some value to set.

By showing all chars, enabling and disabling expansion of tabs into spaces with :set expandtab and :set noexpandtab, setting tabstop and by using for ex. :retab! 4 you can play your way around and switch from tabs only and spaces only, and change the tab column width.

This link, vim settings for python might be useful also

python - Use Vim Retab to solve TabError: inconsistent use of tabs and spaces in indentation?

3 Answers