Sync

Task/Sort-stability/AWK/sort-stability.awk

@@ -0,0 +1,27 @@
+# syntax: GAWK -f SORT_STABILITY.AWK [-v width=x] -v field=x SORT_STABILITY.TXT
+#
+# sort by country: GAWK -f SORT_STABILITY.AWK -v field=1 SORT_STABILITY.TXT
+# sort by city:    GAWK -f SORT_STABILITY.AWK -v field=2 SORT_STABILITY.TXT
+#
+# awk sort is not stable. Stability may be achieved by appending the
+# record number, I.E. NR, to each key.
+#
+BEGIN {
+    FIELDWIDTHS = "4 20" # 2 fields: country city
+    PROCINFO["sorted_in"] = "@ind_str_asc"
+    if (width == "") {
+      width = 6
+    }
+}
+{ arr[$field sprintf("%0*d",width,NR)] = $0 }
+END {
+    if (length(NR) > width) {
+      printf("error: sort may still be unstable; change width to %d\n",length(NR))
+      exit(1)
+    }
+    printf("after sorting on field %d:\n",field)
+    for (i in arr) {
+      printf("%s\n",arr[i])
+    }
+    exit(0)
+}