CODEWITHSUNDEEP
r
Lilia Feng
Lilia Feng

Reputation: 67

how to separate a variable based on another variable

I have two variables: x and y. x is included in y. For example,

x            y
1a        abc 1a 39d 
2b        abc 2b 32i
3c        ad ab 3c 32a 32
9d       ab acb  9d 2d
N/A        abc 329d

I would like to separate y into two parts based on x, like following. 

x            y1               y2              
1a          abc              39d 
2b          abc              32i
3c          ad ab           32a 32
93d        ab acb             2d
N/A         abc               329d

Any suggestions are appreciated, thanks!

I know that gregexpr() can find the location of a pattern, but how to find the first and last location of the string "x" in order to separate y?

Upvotes: 0

Views: 37

Answers (2)

Ronak Shah
Ronak Shah

Reputation: 388982

You could almost get what you want using strsplit by splitting y on x

df1 <- cbind(df[1], do.call("rbind", strsplit(df$y, df$x)))
df1

#    x       1        2
#1  1a     abc       39d
#2  2b     abc       32i
#3  3c   ad ab    32a 32
#4  9d  ab acb        2d
#5 N/A abc 329d abc 329d

For "N/A" cases as it will always have two parts we can split it on whitespace and replace them in particular indices.

inds <- df$x == "N/A"
df1[inds, 2:3] <- do.call("rbind", strsplit(df$y[inds], "\\s+"))

df1
#    x    1    2
#1  1a  abc 329d
#2  2b 329d  abc
#3  3c  abc 329d
#4  9d 329d  abc
#5 N/A  abc 329d

Upvotes: 1

moodymudskipper
moodymudskipper

Reputation: 47320

Maybe something like this ?

df1 <- read.table(text=
                    "x            y
                  1a        'abc 1a 39d' 
                  2b        'abc 2b 32i'
                  3c        'ad ab 3c 32a 32'
                  9d       'ab acb  9d 2d'
                  N/A        'abc 329d'",h=T,strin=F)


library(tidyverse)
df1 %>% 
  mutate(y = ifelse(x == "N/A", 
                    str_replace_all(y," "," | "),
                    str_replace_all(y,x,"|"))) %>%
  separate(y,c("y1","y2"),sep = " \\| ")

#     x      y1     y2
# 1  1a     abc    39d
# 2  2b     abc    32i
# 3  3c   ad ab 32a 32
# 4  9d ab acb      2d
# 5 N/A     abc   329d

Upvotes: 1

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