# # This script demonstrates the use of assignment operators and # sequential expression evaluation to track data points as they # are read in. # # We use the '=' and ',' operators to track the running total # and previous 5 values of a stream of input data points. # # Ethan A Merritt - August 2007 # # Define a function to calculate average over previous 5 points # set title \ "Demonstrate use of assignment and serial evaluation operators\n" \ . "to accumulate statistics as successive data lines are read in\n" set key invert box center right reverse Left set xtics nomirror set ytics nomirror set border 3 samples(x) = $0 > 4 ? 5 : ($0+1) avg5(x) = (shift5(x), (back1+back2+back3+back4+back5)/samples($0)) shift5(x) = (back5 = back4, back4 = back3, back3 = back2, back2 = back1, back1 = x) # # Initialize a running sum # init(x) = (back1 = back2 = back3 = back4 = back5 = sum = 0) # # Plot data, running average and cumulative average # datafile = 'silver.dat' set xrange [0:57] set style data linespoints plot sum = init(0), \ datafile using 0:2 title 'data' lw 2 lc rgb 'forest-green', \ '' using 0:(avg5($2)) title "running mean over previous 5 points" pt 7 ps 0.5 lw 1 lc rgb "blue", \ '' using 0:(sum = sum + $2, sum/($0+1)) title "cumulative mean" pt 1 lw 1 lc rgb "dark-red"
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