sample - filter for random sampling of input.
sample [-h] [-d files] [-n count] [-p percent] [-s seed] [FILE ...]
sample FILE # randomly choose & print 4 lines from file, in order input | sample # same, from stream (file defaults to stdin) sample FILE FILE2 FILE3 # randomly choose 4 lines between multiple input files sample -n 10 FILE # choose 10 lines sample -p 10 FILE # 10% chance of choosing each line input | sample -p 5 # randomly print 5% of input lines input | sample -d a,b,c # append input to files a, b, and c, even odds input | sample -d a,b,c, # append input to files a, b, c, or /dev/null
-h - Print help -d FILES - randomly deal lines to multiple files (',' separated) -n COUNT - Set sample count (default: -n 4) -p PERC - Sample PERC percent for input(s) (',' separated) -s SEED - Set a specific random seed (default: seed based on time)
Sampling by count (-n) works in O(n) space (but n=number of samples, not input size) and outputs samples when end of input is reached. The input order of the samples is preserved.
Sampling by percentage (-p) works in constant space (no data is accumulated) and outputs as each group of lines is read.
If multiple files are used, they can have custom probability percentages:
input | sample -d a,b,c,d -p 0.5,0.25,0.125,0.125
If the last probability is omitted, it will take all remaining:
input | sample -d a,b,c,d -p 0.5,0.25,0.125,
If a file is omitted, it will behave like /dev/null:
input | sample -d a,b,c, -p 0.25,0.25,0.25,0.25
If probabilities are between 1 and 100, they will be treated as percentages:
input | sample -d a,b,c,d -p 25,25,25,25