使用tidyr :: separate与sep =“”将一列分成多个列

Question

df <- data.frame(category = c("X", "Y"), sequence = c("AAT.G", "CCG-T"), stringsAsFactors = FALSE)

df
 category sequence
1        X     AAT.G
2        Y     CCG-T

我想将该列sequence分为5列（每个字符一个）。我试图这样做，tidyr::separate但它在内部使用了stringi::stri_split_regex不接受空字符串作为分隔符的方式（尽管sep参数应使用正则表达式）。

library(tidyr)
separate(df, sequence, into = paste0("V", 1:5), sep="")

Error: Values not split into 5 pieces at 1, 2
In addition: Warning messages:
1: In stringi::stri_split_regex(value, sep, n_max) :
  empty search patterns are not supported
2: In stringi::stri_split_regex(value, sep, n_max) :
  empty search patterns are not supported

预期的输出如下所示：

  category V1 V2 V3 V4 V5
1        X  A  A  T  .  G
2        Y  C  C  G  -  T

Answer 1

你可以用extractfrom来做到这一点tidyr

library(tidyr)
extract(df, sequence, into=paste0('V', 1:5), '(.)(.)(.)(.)(.)')
#  category V1 V2 V3 V4 V5
#1        X  A  A  T  .  G
#2        Y  C  C  G  -  T

或者创建一个分隔符gsub并将其sep用作separator

library(dplyr)
library(tidyr)
df %>% 
   mutate(sequence=gsub('(?<=.)(?=.)', ',', sequence, perl=TRUE)) %>% 
   separate(sequence, into=paste0('V', 1:5), sep=",")
#  category V1 V2 V3 V4 V5
#1        X  A  A  T  .  G
#2        Y  C  C  G  -  T

或者你可以使用cSplit

library(splitstackshape)
setnames(cSplit(df, 'sequence', '', stripWhite=FALSE),
             2:6, paste0('V', 1:5))[]
#   category V1 V2 V3 V4 V5
#1:        X  A  A  T  .  G
#2:        Y  C  C  G  -  T