À partir d'un vecteur de 18 valeurs de texte, je veux générer 153 paires où aucune des paires n'est identique. Y a-t-il un moyen de faire cela avec la fonction exemple?
J'ai inclus ce que j'ai jusqu'à présent ci-dessous, c'est basique maintenant, je veux juste savoir comment construire dessus pour obtenir la fonction que je veux p>
#vector of species included in the survey
rewildingspps<c("lynx","wolf","wildcat","bison","beaver","moose","boar","owl","goshawk","osprey","nightheron","pelican","spoonbill","stork","eagle","bustard","crane","capercaillie")
#sample- will pick 2 species randomly from the rewildingspps vector
sample(rewildingspps,2)
3 Réponses :
matrix( unlist( combn( rewildingspps, 2 ) ), ncol = 2 )
[,1] [,2]
[1,] "lynx" "owl"
[2,] "wolf" "moose"
[3,] "lynx" "goshawk"
[4,] "wildcat" "moose"
[5,] "lynx" "osprey"
[6,] "bison" "moose"
[7,] "lynx" "nightheron"
[8,] "beaver" "moose"
[9,] "lynx" "pelican"
[10,] "moose" "moose"
[11,] "lynx" "spoonbill"
[12,] "boar" "moose"
[13,] "lynx" "stork"
[14,] "owl" "moose"
[15,] "lynx" "eagle"
[16,] "goshawk" "moose"
[17,] "lynx" "bustard"
[18,] "osprey" "moose"
[19,] "lynx" "crane"
[20,] "nightheron" "moose"
[21,] "lynx" "capercaillie"
[22,] "pelican" "boar"
[23,] "lynx" "owl"
[24,] "spoonbill" "boar"
[25,] "lynx" "goshawk"
[26,] "stork" "boar"
[27,] "lynx" "osprey"
[28,] "eagle" "boar"
[29,] "lynx" "nightheron"
[30,] "bustard" "boar"
[31,] "lynx" "pelican"
[32,] "crane" "boar"
[33,] "lynx" "spoonbill"
[34,] "capercaillie" "boar"
[35,] "wolf" "stork"
[36,] "wildcat" "boar"
[37,] "wolf" "eagle"
[38,] "bison" "boar"
[39,] "wolf" "bustard"
[40,] "beaver" "boar"
[41,] "wolf" "crane"
[42,] "moose" "boar"
[43,] "wolf" "capercaillie"
[44,] "boar" "owl"
[45,] "wolf" "goshawk"
[46,] "owl" "owl"
[47,] "wolf" "osprey"
[48,] "goshawk" "owl"
[49,] "wolf" "nightheron"
[50,] "osprey" "owl"
[51,] "wolf" "pelican"
[52,] "nightheron" "owl"
[53,] "wolf" "spoonbill"
[54,] "pelican" "owl"
[55,] "wolf" "stork"
[56,] "spoonbill" "owl"
[57,] "wolf" "eagle"
[58,] "stork" "owl"
[59,] "wolf" "bustard"
[60,] "eagle" "owl"
[61,] "wolf" "crane"
[62,] "bustard" "owl"
[63,] "wolf" "capercaillie"
[64,] "crane" "goshawk"
[65,] "wolf" "osprey"
[66,] "capercaillie" "goshawk"
[67,] "wildcat" "nightheron"
[68,] "bison" "goshawk"
[69,] "wildcat" "pelican"
[70,] "beaver" "goshawk"
[71,] "wildcat" "spoonbill"
[72,] "moose" "goshawk"
[73,] "wildcat" "stork"
[74,] "boar" "goshawk"
[75,] "wildcat" "eagle"
[76,] "owl" "goshawk"
[77,] "wildcat" "bustard"
[78,] "goshawk" "goshawk"
[79,] "wildcat" "crane"
[80,] "osprey" "goshawk"
[81,] "wildcat" "capercaillie"
[82,] "nightheron" "osprey"
[83,] "wildcat" "nightheron"
[84,] "pelican" "osprey"
[85,] "wildcat" "pelican"
[86,] "spoonbill" "osprey"
[87,] "wildcat" "spoonbill"
[88,] "stork" "osprey"
[89,] "wildcat" "stork"
[90,] "eagle" "osprey"
[91,] "wildcat" "eagle"
[92,] "bustard" "osprey"
[93,] "wildcat" "bustard"
[94,] "crane" "osprey"
[95,] "wildcat" "crane"
[96,] "capercaillie" "osprey"
[97,] "bison" "capercaillie"
[98,] "beaver" "nightheron"
[99,] "bison" "pelican"
[100,] "moose" "nightheron"
[101,] "bison" "spoonbill"
[102,] "boar" "nightheron"
[103,] "bison" "stork"
[104,] "owl" "nightheron"
[105,] "bison" "eagle"
[106,] "goshawk" "nightheron"
[107,] "bison" "bustard"
[108,] "osprey" "nightheron"
[109,] "bison" "crane"
[110,] "nightheron" "nightheron"
[111,] "bison" "capercaillie"
[112,] "pelican" "pelican"
[113,] "bison" "spoonbill"
[114,] "spoonbill" "pelican"
[115,] "bison" "stork"
[116,] "stork" "pelican"
[117,] "bison" "eagle"
[118,] "eagle" "pelican"
[119,] "bison" "bustard"
[120,] "bustard" "pelican"
[121,] "bison" "crane"
[122,] "crane" "pelican"
[123,] "bison" "capercaillie"
[124,] "capercaillie" "spoonbill"
[125,] "beaver" "stork"
[126,] "moose" "spoonbill"
[127,] "beaver" "eagle"
[128,] "boar" "spoonbill"
[129,] "beaver" "bustard"
[130,] "owl" "spoonbill"
[131,] "beaver" "crane"
[132,] "goshawk" "spoonbill"
[133,] "beaver" "capercaillie"
[134,] "osprey" "stork"
[135,] "beaver" "eagle"
[136,] "nightheron" "stork"
[137,] "beaver" "bustard"
[138,] "pelican" "stork"
[139,] "beaver" "crane"
[140,] "spoonbill" "stork"
[141,] "beaver" "capercaillie"
[142,] "stork" "eagle"
[143,] "beaver" "bustard"
[144,] "eagle" "eagle"
[145,] "beaver" "crane"
[146,] "bustard" "eagle"
[147,] "beaver" "capercaillie"
[148,] "crane" "bustard"
[149,] "beaver" "crane"
[150,] "capercaillie" "bustard"
[151,] "moose" "capercaillie"
[152,] "boar" "crane"
[153,] "moose" "capercaillie"
La fonction combn a un argument pratique FUN :
combn(rewildingspps,2)
Ou encore mieux, à partir d'un commentaire ci-dessus:
combn(18,2,FUN = function(x) rewildingspps[x])
En plus de la réponse de @ joran, puisque le titre dit "Sélection aléatoire des paires", nous pouvons randomiser les paires générées à partir de combn en échantillonner les indices (paires de combn sont classés en fonction de l'ordre du vecteur d'entrée, donc ce n'est pas aléatoire):
[,1] [,2] [1,] "boar" "stork" [2,] "wildcat" "stork" [3,] "owl" "eagle" [4,] "wolf" "boar" [5,] "goshawk" "pelican" [6,] "wildcat" "beaver" [7,] "osprey" "nightheron" [8,] "lynx" "spoonbill" [9,] "lynx" "nightheron" [10,] "lynx" "osprey" [11,] "owl" "spoonbill" [12,] "owl" "nightheron" [13,] "moose" "bustard" [14,] "goshawk" "capercaillie" [15,] "wolf" "stork" [16,] "pelican" "stork" [17,] "nightheron" "spoonbill" [18,] "osprey" "pelican" [19,] "osprey" "crane" [20,] "spoonbill" "bustard" ...
Sortie:
XXX
Ainsi,
combn (18,2)génère l'ensemble exact de 153 paires d'entiers non dupliquées. Utilisez-les pour indexer (sous-ensemble) votre vecteur?Vous avez en fait besoin de combinaisons , que vous pouvez obtenir avec
combn (rewildingspps, m = 2).En fait, probablement juste
combn (18,2, FUN = function (x) rewildingspps [x])vous donnera ce que vous voulez directement?@joran ou
t (combn (rewildingspps, 2))@avid_useR Oui, encore mieux!