如何使用r省略data.frame中单词的倒数

我一直在网上寻找答案，但似乎无法找到答案

我有一组标记，并使用

expand.grid（）

查找它们的组合：

# TICKERS
A <- c("AIR", "AFAP", "AAL", "CECE", "ASA", "AVX")
# FIND COMBINATIONS
B <- expand.grid(A,A,stringsAsFactors=FALSE)

---

使用OP的初始输出，我们可以使用

apply

with

MARGIN=1

，对“B”进行

逐行排序，然后使用
duplicated
获得“d1”行的非重复逻辑索引，并将其用于子集“B”

d1 <- as.data.frame(t(apply(B, 1, sort)))
B1 <- B[!duplicated(d1),]
head(B1, 10)
#   Var1 Var2
#1   AIR  AIR
#2  AFAP  AIR
#3   AAL  AIR
#4  CECE  AIR
#5   ASA  AIR
#6   AVX  AIR
#8  AFAP AFAP
#9   AAL AFAP
#10 CECE AFAP
#11  ASA AFAP

改用软件包
gtools
：

library(gtools)
A <- c("AIR", "AFAP", "AAL", "CECE", "ASA", "AVX")

combinations(length(A), 2, A, repeats = FALSE)

#       [,1]   [,2]  
#  [1,] "AAL"  "AFAP"
#  [2,] "AAL"  "AIR" 
#  [3,] "AAL"  "ASA" 
#  [4,] "AAL"  "AVX" 
#  [5,] "AAL"  "CECE"
#  [6,] "AFAP" "AIR" 
#  [7,] "AFAP" "ASA" 
#  [8,] "AFAP" "AVX" 
#  [9,] "AFAP" "CECE"
# [10,] "AIR"  "ASA" 
# [11,] "AIR"  "AVX" 
# [12,] "AIR"  "CECE"
# [13,] "ASA"  "AVX" 
# [14,] "ASA"  "CECE"
# [15,] "AVX"  "CECE"

库（gtools）
A.
library(data.table)
CJ(A, A)[V1>=V2]

library(gtools)
A <- c("AIR", "AFAP", "AAL", "CECE", "ASA", "AVX")

combinations(length(A), 2, A, repeats = FALSE)

#       [,1]   [,2]  
#  [1,] "AAL"  "AFAP"
#  [2,] "AAL"  "AIR" 
#  [3,] "AAL"  "ASA" 
#  [4,] "AAL"  "AVX" 
#  [5,] "AAL"  "CECE"
#  [6,] "AFAP" "AIR" 
#  [7,] "AFAP" "ASA" 
#  [8,] "AFAP" "AVX" 
#  [9,] "AFAP" "CECE"
# [10,] "AIR"  "ASA" 
# [11,] "AIR"  "AVX" 
# [12,] "AIR"  "CECE"
# [13,] "ASA"  "AVX" 
# [14,] "ASA"  "CECE"
# [15,] "AVX"  "CECE"