Shell Programming and Scripting

I wasn't sure if sensor M01072-5 was missing or if sensor M01072-4 was there by mistake. You originally said that there would be three to six measurements per sensor and both of these sensors only had two measurements in your sample data.

Sorting your input file takes time and might rearrange the order of lines that have the same sort key, so if picking the 1st measurement from measurements with the same calculated "best" measurement matters, Yoda's suggestion is probably much better than sorting and then using a simpler awk script.

The script rdrtx1 just provided also looks good as long as none of your sensor reading calculations ($6 * $7) produce negative values.

I'm not sure I understand rdrtx1's script (please explain; thanks!), but it will not print the best measurement (i.e. the one with max $6*$7), but the first line for each sensor.

RudiC is correct; rdrtx1's script uses the array a[$1] to store both the computed value of the best measurement and the contents of the line containing the best measurement. It can't do both.

Yoda's script uses a tab as the field separator (where the requested separator seems to be four spaces) and not only prints the line with the best measurement for each sensor, but also the computed measurement (which was not requested). Rearranging Yoda's script, changing OFS, leaving off the computed measurement, and dropping one unneeded assignment ($1 = $1); I came up with this script:

Code:

awk '
{       V = $6 * $7
        if(!($1 in A) || A[$1] < V) {
                A[$1] = V
                R[$1] = $0
        }
}
END {   for(k in R)
                print R[k]
}
' OFS='    ' infile.txt

which produces the following output:

Code:

M01072-1    FJ973371    238617596    400    1979    97.91    383    8    0    1    383    1105    723
M01072-2    EF205010    147743297    443    1269    99.55    443    2    0    1    443    869    427
M01072-4    HM483399    299790116    443    3656    92.63    448    23    9    1    443    3314    2872
M01072-5    AF183464    6120004    403    2120    93.20    397    22    5    8    403    539    931
M01072-6    AF395513    15281673    403    2104    93.25    400    12    13    1    392    510    902
M01072-7    EF205010    147743297    358    1269    99.43    351    2    0    8    358    791    441
M01011-2    HQ670228    339699497    443    1313    93.72    446    22    6    1    443    871    429

which matches the requested output except that the output order is different and the output for sensor M01072-5 (shown in red above) was missed in the original request. If the output order difference is important, you'll need to specify what order is needed. We can then either sort the results externally or modify the awk script (to preserve the input order) depending on what output order is required.

As always, if you're going to use this on a Solaris system; use /usr/xpg4/bin/awk, /usr/xpg6/bin/awk, or nawk instead of /usr/bin/awk or /bin/awk.

Hope this helps.

Dear All,

I tested the awk script provided by rdrtxt and it worked ... although I see now the double assignment problem.

---------- Post updated at 04:47 PM ---------- Previous update was at 04:24 PM ----------

Dear Don Cragun,

thanks for pointing out the problem with rdrtx1's awk script. I used a sorted table and did not realize the problem. I will use the modified script originally suggested by Yoda. Thanks!