Sed/Awk join odd and even lines - platform independent-CodePudding

hi all im trying to make this

2022-11-14 18:49:59             Indicator is < 3    
1       No
2022-11-14 18:49:59             Indicator is < 10   
1       No
2022-11-14 18:49:59             Indicator is < 22   
1       No
2022-11-14 18:49:59             Indicator is < 1    
1       No

into

2022-11-14 18:49:59             Indicator is < 3    1       No
2022-11-14 18:49:59             Indicator is < 10   1       No
2022-11-14 18:49:59             Indicator is < 22   1       No
2022-11-14 18:49:59             Indicator is < 1    1       No

i found that you can use sed 's/something/some//2' for every second encounter but how to make it for 1st, 3th, 5th,.... and so one

CodePudding user response：

$ awk '{printf "%s%s", $0, (NR%2 ? OFS : ORS)}' file
2022-11-14 18:49:59             Indicator is < 3     1       No
2022-11-14 18:49:59             Indicator is < 10    1       No
2022-11-14 18:49:59             Indicator is < 22    1       No
2022-11-14 18:49:59             Indicator is < 1     1       No

The minor differences between this and @AndreWildberg's answer are:

This holds no lines in memory while Andres holds 1 line (not an issue, just a difference).
If there were an odd number of lines in the input, this would print all of them (though with a blank instead of a terminating newline at the end of the last line) while Andres would delete the last line (but produce a terminating newline), e.g.:

$ seq 5 | awk '{printf "%s%s", $0, (NR%2 ? OFS : ORS)}'
1 2
3 4
5 $

$ seq 5 | awk 'NR % 2 == 0{print prev, $0} {prev = $0}'
1 2
3 4
$

CodePudding user response：

Another approach

$ paste - - <file

2022-11-14 18:49:59             Indicator is < 3        1       No
2022-11-14 18:49:59             Indicator is < 10       1       No
2022-11-14 18:49:59             Indicator is < 22       1       No
2022-11-14 18:49:59             Indicator is < 1        1       No

or (more fragile)

$ pr -w112 -2at file

2022-11-14 18:49:59             Indicator is < 3        1       No
2022-11-14 18:49:59             Indicator is < 10       1       No
2022-11-14 18:49:59             Indicator is < 22       1       No
2022-11-14 18:49:59             Indicator is < 1        1       No

CodePudding user response：

Try this with awk using modulo.

$ awk -v val=2 'NR % val == 0{print prev, $0} {prev = $0}' file
2022-11-14 18:49:59             Indicator is < 3     1       No
2022-11-14 18:49:59             Indicator is < 10    1       No
2022-11-14 18:49:59             Indicator is < 22    1       No
2022-11-14 18:49:59             Indicator is < 1     1       No

It looks at the record number NR and calculates modulo 2 of it. Since every second line comes out as 0 it will then print the previous prev and the current $0 line.

Remarks:

Printing last odd lines is undefined, the given example is clear. It can even be seen as a feature to not print them (even out a data set).
This keeps execution time in mind and is a fast approach.