Est-ce que quelqu'un connaît un outil Linux spécialement conçu pour traiter les fichiers comme des ensembles et effectuer des opérations d'ensemble sur eux ? Comme la différence, l'intersection, etc ?
Réponse acceptée :
En supposant que les éléments sont des chaînes de caractères autres que NUL et newline (attention, cette nouvelle ligne est cependant valide dans les noms de fichiers), vous pouvez représenter un ensemble sous forme de fichier texte avec un élément par ligne et utilisez certains des utilitaires Unix standard.
Définir l'adhésion
$ grep -Fxc 'element' set # outputs 1 if element is in set
# outputs >1 if set is a multi-set
# outputs 0 if element is not in set
$ grep -Fxq 'element' set # returns 0 (true) if element is in set
# returns 1 (false) if element is not in set
$ awk '$0 == "element" { s=1; exit }; END { exit !s }' set
# returns 0 if element is in set, 1 otherwise.
$ awk -v e='element' '$0 == e { s=1; exit } END { exit !s }'
Définir l'intersection
$ comm -12 <(sort set1) <(sort set2) # outputs intersect of set1 and set2
$ grep -xF -f set1 set2
$ sort set1 set2 | uniq -d
$ join -t <(sort A) <(sort B)
$ awk '!done { a[$0]; next }; $0 in a' set1 done=1 set2
Définir l'égalité
$ cmp -s <(sort set1) <(sort set2) # returns 0 if set1 is equal to set2
# returns 1 if set1 != set2
$ cmp -s <(sort -u set1) <(sort -u set2)
# collapses multi-sets into sets and does the same as previous
$ awk '{ if (!($0 in a)) c++; a[$0] }; END{ exit !(c==NR/2) }' set1 set2
# returns 0 if set1 == set2
# returns 1 if set1 != set2
$ awk '{ a[$0] }; END{ exit !(length(a)==NR/2) }' set1 set2
# same as previous, requires >= gnu awk 3.1.5
Définir la cardinalité
$ wc -l < set # outputs number of elements in set
$ awk 'END { print NR }' set
$ sed '$=' set
Test de sous-ensemble
$ comm -23 <(sort -u subset) <(sort -u set) | grep -q '^'
# returns true iff subset is not a subset of set (has elements not in set)
$ awk '!done { a[$0]; next }; { if !($0 in a) exit 1 }' set done=1 subset
# returns 0 if subset is a subset of set
# returns 1 if subset is not a subset of set
Définir l'union
$ cat set1 set2 # outputs union of set1 and set2
# assumes they are disjoint
$ awk 1 set1 set2 # ditto
$ cat set1 set2 ... setn # union over n sets
$ sort -u set1 set2 # same, but doesn't assume they are disjoint
$ sort set1 set2 | uniq
$ awk '!a[$0]++' set1 set2 # ditto without sorting
Définir le complément
$ comm -23 <(sort set1) <(sort set2)
# outputs elements in set1 that are not in set2
$ grep -vxF -f set2 set1 # ditto
$ sort set2 set2 set1 | uniq -u # ditto
$ awk '!done { a[$0]; next }; !($0 in a)' set2 done=1 set1
Définir la différence symétrique
$ comm -3 <(sort set1) <(sort set2) | tr -d 't' # assumes not tab in sets
# outputs elements that are in set1 or in set2 but not both
$ sort set1 set2 | uniq -u
$ cat <(grep -vxF -f set1 set2) <(grep -vxF -f set2 set1)
$ grep -vxF -f set1 set2; grep -vxF -f set2 set1
$ awk '!done { a[$0]; next }; $0 in a { delete a[$0]; next }; 1;
END { for (b in a) print b }' set1 done=1 set2
Ensemble de puissance
Tous les sous-ensembles possibles d'un ensemble s'affichent séparés, un par ligne :
$ p() { [ "$#" -eq 0 ] && echo || (shift; p "[email protected]") |
while read r; do printf '%s %sn%sn' "$1" "$r" "$r"; done; }
$ p $(cat set)
(en supposant que les éléments ne contiennent pas SPC, TAB (en supposant la valeur par défaut de $IFS ), barre oblique inverse, caractères génériques).
Définir le produit cartésien
$ while IFS= read -r a; do while IFS= read -r b; do echo "$a, $b"; done < set1; done < set2
$ awk '!done { a[$0]; next }; { for (i in a) print i, $0 }' set1 done=1 set2
Test d'ensemble disjoint
$ comm -12 <(sort set1) <(sort set2) # does not output anything if disjoint
$ awk '++seen[$0] == 2 { exit 1 }' set1 set2 # returns 0 if disjoint
# returns 1 if not
Test d'ensemble vide
$ wc -l < set # outputs 0 if the set is empty
# outputs >0 if the set is not empty
$ grep -q '^' set # returns true (0 exit status) unless set is empty
$ awk '{ exit 1 }' set # returns true (0 exit status) if set is empty
Minimum
$ sort set | head -n 1 # outputs the minimum (lexically) element in the set
$ awk 'NR == 1 { min = $0 }; $0 < min { min = $0 }; END { print min }'
# ditto, but does numeric comparison when elements are numerical
Maximum
$ sort test | tail -n 1 # outputs the maximum element in the set
$ sort -r test | head -n 1
$ awk '$0 > max { max = $0 }; END { print max }'
# ditto, but does numeric comparison when elements are numerical
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