Tag Archive
amateur astronomy awk bash b[e] supergiant cartoon conference convert evolved star exoplanet fedora figaro fits fun galaxy iraf large magellanic cloud latex linux lmc machine learning magellanic clouds massive star matplotlib meteor mypaper paper peblo photometry planet pro-am pyraf python red supergiant scisoft skinakas observatory small magellanic cloud smc spectroscopy starlink talk ubuntu university of crete video x-ray yellow hypergiant
Mean value and standard deviation of a column using awk
In order to get the mean value of column 1 (or any other) you type:
$ awk 'BEGIN{s=0;}{s=s+$1;}END{print s/NR;}' file
In order to get the standard deviation of column 1 you type:
$ awk '{sum+=$1; sumsq+=$1*$1} END {print sqrt(sumsq/NR - (sum/NR)^2)}' file
or
$ awk '{delta = $1 - avg; avg += delta / NR; mean2 += delta * ($1 - avg); } END { print sqrt(mean2 / NR); }' file
The second option is working better with large numbers of data, without having the possibility for overflow.
Sources: utah.edu/awk , commandlinefu.com/standard deviation with awk