Add AWK script to sample a column of values

Author: kgryte

tools/awk/sample.awk

@@ -0,0 +1,37 @@
+#!/usr/bin/env awk -f
+#
+# Samples a column of values.
+#
+# Usage: sample prob seed
+#
+# Input:
+#   - a column of values
+#
+# Arguments:
+#   - prob: success probability
+#   - seed: pseudorandom number generator seed
+#
+# Output:
+#   - sample values
+#
+# Example:
+#   $ sample 0.1 $RANDOM
+
+BEGIN {
+	if (ARGC == 1) {
+		prob = 0.5
+	} else if (ARGC == 2) {
+		prob = ARGV[1]
+		ARGV[1] = ""
+	} else {
+		prob = ARGV[1]
+		srand(ARGV[2])
+		ARGV[1] = ""
+		ARGV[2] = ""
+	}
+	# No filenames so force stdin:
+	ARGV[ARGC++] = "-"
+}
+rand() <= prob {
+	print $0
+}