How to modify list of lists using str.format() so floats are 3 decimals and other data types remain-CodePudding

I have a list of lists that is very big, and looks like this:

list_of_lists = [[0,'pan', 17.892, 4.6555], [4, 'dogs', 19.2324, 1.4564], ...]

I need to modify it using the str.format() so the floats go to 3 decimal places and the rest of the data stays in its correct format. I also need to add a tab between each list entry so it looks organized and somewhat like this:

0   'pan'   17.892   4.655
4   'dogs'  19.232   1.456
...

And so on.

My problem is that I keep getting the error in my for loop and gow to fix it.

for x in list_of_lists:
    print ("{:.2f}".format(x))

TypeError: unsupported format string passed to list.__format__

CodePudding user response：

In your loop you are iterating through a nested list. This means that x is also a list itself, and not a valid argument to the format() function.

If the number of elements in the inner lists are small and it makes sense in the context of the problem, you can simply list all of them as arguments:

list_of_lists = [[0,'pan', 17.892, 4.6555], [4, 'dogs', 19.2324, 1.4564]]

for x in list_of_lists:
    print ("{:d}\t{:s}\t{:.3f}\t{:.3f}".format(x[0], x[1], x[2], x[3]))

These are now tab delimited, and the floats have three decimal places.

CodePudding user response：

for x in list_of_lists:
    print ("{:.2f}".format(x))

This is only looping over the top level array - not the elements inside - therefore you are getting the error.

Try addressing the element individually

# build manually, join with tab-char and print on loop 
for i in s:
    result = []
    result.append( f'{i[0]}' )
    result.append( f'{i[1]}' )
    result.append( f'{i[2]:.3f}' )
    result.append( f'{i[3]:.3f}' )
    print( '\t'.join(result) )

# build in one line and print
for i in s:
    print( f'{i[0]}\t\'{i[1]}\'\t{i[2]:.3f}\t{i[3]:.3f}'

Or as a list comprehension

# build whole line from list comprehension, join on new-line chat
result = [f'{i[0]}\t\'{i[1]}\'\t{i[2]:.3f}\t{i[3]:.3f}' for i in s]
result = '\n'.join(result)
print(result

# all in one line
print( '\n'.join([f'{i[0]}\t\'{i[1]}\'\t{i[2]:.3f}\t{i[3]:.3f}' for i in s]))