Unix: Print extra column of values to file

Question

I have a .txt file (new_file.txt) with a column of values (200). I need to print another column beside it, with values 0,1/200,2/200.....1. How should I do this? I am new to this, so any suggestions will be great!

I know that seq 0 0.005 1 >new_file.txt will print it into the file, but it overwrites the values already present. I want to add these numbers as another column beside the values already present in the file.

The input is like:

2.41
2.56 

etc. in a column. I need it to look like

2.41 0
2.56 0.005

etc. in a column. I need to have a tab in between.

Answer 1

With seq and paste:

seq 0 0.005 1 | paste newfile.txt - > newerfile.txt

With awk

awk '{$2 = 0.005*(NR-1)} 1' OFS='\t' newfile.txt > newerfile.txt

Depending on your version of awk, you may be able to modify newfile.txt in place.

Answer 2

As mentioned in comments, paste is the best option to do what you want.

 paste new_file.txt <sequence file>

If you want to generate sequence at run time

seq 0 0.005 1 | paste new_file.txt /dev/stdin

Example (for 5 records in new_file.txt)

~$ seq 0 0.005 0.020 | paste new_file.txt /dev/stdin
2.41    0.000
2.56    0.005
2.71    0.010
2.86    0.015
3.01    0.020

Note: If any of the file/command have extra rows in it, then corresponding rows in output would be blank. So make sure that both files have same number of row.

Answer 3

You can do it using GNU dc as follows:

< new_file.txt tr -- - _ | dc -e "[q]sq [?z1=qrd1<qrn32anp0.005+dd=?]s? 0l?x"

---

Explanation:

dc -e '
# macro for quitting
[q]sq

# macro to read next line and perform operations
[
   ? z1=q  # read next line and quit when it is empty. The 1 is apriori
   r       # else, reverse the stack elements so that sum is top of stack now
   d1<q    # quit if current sum is more than 1
   r       # else, reverse the stack elements so that line is top of stack now
   n 32an p # print the line, space (32a is ascii decimal for space), & print current sum
   0.005+   # update the current sum for next round
   dd=?     # recursively invoke itself for more.... its a loop essentially
]s?

# initialize stack and start operations
0 l?x
'