Shell: Add set operations on lines (union, intersection, difference, symdiff, is-subset)

Author: jdevera

home/dot_config/zsh/exact_private_zsh.d/private_010_functions_text.zsh

@@ -145,3 +145,30 @@ function echoe()
 {
     echo "$@" 1>&2
 }
+
+##############################################################################
+# Set operations on lines
+#
+# Each function takes two files (or process substitutions) as arguments.
+# Input is sorted and deduplicated automatically.
+#
+# Usage: set-difference <(cmd1) <(cmd2)
+#
+# @tags: canbescript filter
+
+# A ∪ B — all lines from either input, deduplicated
+function set-union()        { sort -u "$1" "$2"; }
+
+# A ∩ B — only lines present in both inputs
+function set-intersection() { comm -12 <(sort -u "$1") <(sort -u "$2"); }
+
+# A \ B — lines in the first input but not in the second
+function set-difference()   { comm -23 <(sort -u "$1") <(sort -u "$2"); }
+
+# A △ B — lines in either input but not in both (symmetric difference)
+# Not using comm -3 directly because it prepends a tab to one column's output.
+function set-symdiff()      { { set-difference "$1" "$2"; set-difference "$2" "$1"; } | sort; }
+
+# A ⊆ B — true (exit 0) if all lines in the first input are also in the second
+function set-is-subset()    { [[ -z $(set-difference "$1" "$2") ]]; }
+##############################################################################

home/exact_private_dot_bash.d/private_010_functions_text.sh

@@ -147,5 +147,32 @@ function echoe()
     echo "$@" 1>&2
 }
 
+##############################################################################
+# Set operations on lines
+#
+# Each function takes two files (or process substitutions) as arguments.
+# Input is sorted and deduplicated automatically.
+#
+# Usage: set-difference <(cmd1) <(cmd2)
+#
+# @tags: canbescript filter
+
+# A ∪ B — all lines from either input, deduplicated
+function set-union()        { sort -u "$1" "$2"; }
+
+# A ∩ B — only lines present in both inputs
+function set-intersection() { comm -12 <(sort -u "$1") <(sort -u "$2"); }
+
+# A \ B — lines in the first input but not in the second
+function set-difference()   { comm -23 <(sort -u "$1") <(sort -u "$2"); }
+
+# A △ B — lines in either input but not in both (symmetric difference)
+# Not using comm -3 directly because it prepends a tab to one column's output.
+function set-symdiff()      { { set-difference "$1" "$2"; set-difference "$2" "$1"; } | sort; }
+
+# A ⊆ B — true (exit 0) if all lines in the first input are also in the second
+function set-is-subset()    { [[ -z $(set-difference "$1" "$2") ]]; }
+##############################################################################
+
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