如何将字符串拆分为具有1/0值标志的列向量？

Question

我有这样的角色矢量:

a <- c("a,b,c", "a,b", "a,b,c,d")

我想要做的是创建一个如下所示的数据框:

   a    b    c    d
1] 1    1    1    0
2] 1    1    0    0
3] 1    1    1    1

我有一种感觉,我需要使用的某种组合read.table和reshape,但我真的很挣扎.任何和帮助赞赏.

Answer 1

您可以尝试cSplit_e我的"splitstackshape"包:

library(splitstackshape)
a <- c("a,b,c", "a,b", "a,b,c,d")
cSplit_e(as.data.table(a), "a", ",", type = "character", fill = 0)
#          a a_a a_b a_c a_d
# 1:   a,b,c   1   1   1   0
# 2:     a,b   1   1   0   0
# 3: a,b,c,d   1   1   1   1
cSplit_e(as.data.table(a), "a", ",", type = "character", fill = 0, drop = TRUE)
#    a_a a_b a_c a_d
# 1:   1   1   1   0
# 2:   1   1   0   0
# 3:   1   1   1   1

还有mtabulate"qdapTools":

library(qdapTools)
mtabulate(strsplit(a, ","))
#   a b c d
# 1 1 1 1 0
# 2 1 1 0 0
# 3 1 1 1 1

一个很直接的基础R的方法是使用table沿着stack和strsplit:

table(rev(stack(setNames(strsplit(a, ",", TRUE), seq_along(a)))))
#    values
# ind a b c d
#   1 1 1 1 0
#   2 1 1 0 0
#   3 1 1 1 1

Answer 2

另一个复杂的基础R解决方案:

x  <- strsplit(a,",")
xl <- unique(unlist(x))

t(sapply(x,function(z)table(factor(z,levels=xl))))

这使

     a b c d
[1,] 1 1 1 0
[2,] 1 1 0 0
[3,] 1 1 1 1

Answer 3

另一种选择tstrsplit()来自data.table:

library(data.table)
vapply(tstrsplit(a, ",", fixed = TRUE, fill = 0), ">", integer(length(a)), 0L)
#      [,1] [,2] [,3] [,4]
# [1,]    1    1    1    0
# [2,]    1    1    0    0
# [3,]    1    1    1    1