Calculate and round numbers up in bash

Question

I'm struggling with a slight variation on: How to calculate by taking first field and How to round floating point numbers in shell?

I have a file that looks like (space between columns):

1533 C_P.doc
691 C_M.doc
905 G_S.doc
945 J_Z.doc
1549 J_M.doc
1701 L_B.doc

I want to take the column of numbers and divide each number by 65 (but round up), and add a new column (ideally to left) with these numbers included. i.e.

24 1533 C_P.doc
11 691 C_M.doc
14 905 G_S.doc
15 945 J_Z.doc
24 1549 J_M.doc
27 1701 L_B.doc

I would like this in a bash script. Is it possible? If necessary, the middle column can be removed if that makes it easier.

[Ubuntu 14.04]

Answer 1

Through awk and keeping middle column:

awk '{printf("%.f ", ($1/65)+0.5)}1' infile > outfile
24 1533 C_P.doc
11 691 C_M.doc
14 905 G_S.doc
15 945 J_Z.doc
24 1549 J_M.doc
27 1701 L_B.doc

Through awk and without middle column:

awk '{printf("%.f", ($1/65)+0.5); $1=""}1' infile > outfile
24 C_P.doc
11 C_M.doc
14 G_S.doc
15 J_Z.doc
24 J_M.doc
27 L_B.doc

Note that +0.5 is used as substitute for the ceil() function and it rounds up to the next number. And 1 on the end actives the default print.

Answer 2

You can use perl:

$ perl -MPOSIX=ceil -anle '$F[0] = ceil($F[0]/65);print "@F"' file
24 C_P.doc
11 C_M.doc
14 G_S.doc
15 J_Z.doc
24 J_M.doc
27 L_B.doc

Answer 3

If you don't mind using python in shell and assuming that a.txt is your file:

[sreeraj@server ~]$ cat a.txt
1533 C_P.doc
691 C_M.doc
905 G_S.doc
945 J_Z.doc
1549 J_M.doc
1701 L_B.doc
[sreeraj@server ~]$ for i in $(awk -v c=65 '{ print $1/c }' a.txt) ; do python -c 'print int(round('$i',0))' ; done >> b.txt
[sreeraj@server ~]$ paste b.txt a.txt > c.txt
[sreeraj@server ~]$ cat c.txt
24      1533 C_P.doc
11      691 C_M.doc
14      905 G_S.doc
15      945 J_Z.doc
24      1549 J_M.doc
26      1701 L_B.doc
[sreeraj@server ~]$

This will create the file c.txt with the desired output.

How it works:

It uses awk to divide the values in the 1st column of a.txt by 65 and then use python's in-built function round() to round the decimals. Then we create a file c.txt with the output from the 'for' loop and use paste to combine the c.txt and a.txt