[FIXED] How to add zero decimal points to all elements of a matrix in shell

Issue

I have a file containing integer and floating numbers which has 3 columns and many lines. I want to have all the numbers in floating format which 6 significant figures, i.e. the number 2 becomes 2.000000. I already tried this script but it only works for one column. I appreciate if you help me how to due it for the next two columns to or any other one line script which can do the job. Thanks in advance

awk '{printf "%.6f\n",$1}' file

Solution

The script you provided works for only one column because you are only printing the first column in the script. If you have only 3 columns and if the number of columns is fixed you just need to add the other two columns to your print statement to make it work.

For example:

awk '{printf "%.6f %.6f %.6f \n",$1,$2,$3}'

If the number of columns is unknown you can use a loop inside awk to print all the columns. NF will give the total number of records. You can iterate through it and print the results.

awk '{ for (i=1; i<= NF; i++) printf "%.6f ",$i; print "" }' input

You also can use this script to print the three columns as required, if your file only contains three columns (NF is 3 in that case).

As pointed out by @kvantour in comments, an elegant way to write the above one liner is:

awk '{for(i=1;i<=NF;++i) printf "%.6f" (i==NF?ORS:OFS), $i} 

Essentially, both one-liners do the same thing but the ORS (Output Record Separator) and OFS (Output Field Separator) variables give the flexibility to change the output easily and quickly.

So, (i==NF?ORS:OFS) what it does is, if the field is not the last column then OFS is printed (OFS is a space by default) and if it is the last column then ORS is printed (default value of ORS is newline ). Advantage of using these separator variables are, for example, if you want to have two new lines instead of a single newline between rows in the results it can be easily set using ORS="\n\n"

Answered By - j23

Answer Checked By - David Goodson (PHPFixing Volunteer)