Formatting output of CSV data?

Question

I'm fairly new to python and made something that had this output: (The text is in a csv file so so: 1,A 2,B 3,C etc)

Number        Letter

1             A
2             B
3             C
26            Z

Unfortunately, I spent a good amount of time making it using a complicated method in which I manually made spaces like this: Updated Code rn

fx = int(input('Number?\n'))
f=open('nums.txt','r')
lines=f.readlines()
line = lines[fx - 1]
with open('nums.txt','r') as f:
    for i, line in enumerate(f):
        if i >= 5: 
            break
        NUM, LTR, SMB = line.rsplit(',', 1)
        print(NUM.ljust(13) + LTR.ljust(13) + SMB)

How do I get it to make 3 columns? Right now it comes up with a

ValueError: not enough values to unpack (expected 3, got 2)

So is there a simpler method of achieving this that doesn't move the strings around like this:

Number        Letter

1             A
2             B
3             C
26             Z #< string moves with spaces.

If you're looking for fixed-width columns, don't you just want something like '{:<13}{:<13}'.format(26, 'Z') — jonrsharpe
– jonrsharpe, Commented Feb 4, 2017 at 21:30

user2390182 · Accepted Answer · 2017-02-04 21:42:29Z

2

For simple alignment, you can use ljust or rjust. There is also no need to read the entire file for each line you want to process:

with open('numberletter','r') as f:
    for i, line in enumerate(f):
        if i >= 5: 
            break
        number, letter = line.rsplit(',', 1)
        print(number.ljust(13) + letter)

For more complex output formatting, look at str.format() and the formatting syntax

edited Feb 4, 2017 at 21:42

answered Feb 4, 2017 at 21:30

user2390182

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5 Comments

Yaya Over a year ago

What if I wanted to have 3 columns for example: Numbers Letters Symbols

user2390182 Over a year ago

You would apply ljust to the second column, as well. Or better, just use rjust on every column. Right alignment looks better in most cases, anyway ;-)

Yaya Over a year ago

So would it just be NUM, LTR, SMB = line.rsplit(',', 1) print(NUM.ljust(13) + LTR.ljust(13) + SMB)

user2390182 Over a year ago

Yeah, but NUM, LTR, SMB = line.rsplit(',', 2), since you need two splits now...

Yaya Over a year ago

Do you know how I can also add a string along with the file? Right now everytime I try do this: print(NUM.ljust(13) + LTR.ljust(13) + SMB + 'test') the 'test' string moves to the first character of the output like this: test 26 z instead of 26 test z

orvi · Accepted Answer · 2017-02-04 21:48:46Z

-1

You can use sys module for that.

import sys
a=[1,"A"]
sys.stdout.write("%-6s %-50s " % (a[0],a[1]))

answered Feb 4, 2017 at 21:48

orvi

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4 Comments

L3viathan Over a year ago

What does that have to do with sys apart from that you happen to be able to write to sys.stdout? The reason why this works has nothing to do with sys and everything with the (deprecated) string formatting operator %.

Yaya Over a year ago

@L3viathan I think he put sys in there because the print function keeps printing new lines after each output and I requested output with no newlines.

user2390182 Over a year ago

@Yaya print(s, end='') does the same with less effort

L3viathan Over a year ago

For no newlines, add a end='' argument to your call to print.

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