Split

F2 <- F1[rep(1:5,1e6),]  ## 5 million rows

system.time({

system.time({

Thank you all for the help!

LMH, Yes I would like to see the alternative.  I am using this for a
large data set and if the  alternative is more efficient than this
then I would be happy.

On Tue, Sep 22, 2020 at 6:25 PM Bert Gunter <bgunter.4567 at gmail.com>
wrote:

To be clear, I think Rui's solution is perfectly fine and probably

better than what I offer below. But just for fun, I wanted to do it without
the lapply().  Here is one way. I think my comments suffice to explain.

## which are the  non "_" indices?
wh <- grep("_",F1$text, fixed = TRUE, invert = TRUE)
## paste "_." to these
F1[wh,"text"] <- paste(F1[wh,"text"],".",sep = "_")
## Now strsplit() and unlist() them to get a vector
z <- unlist(strsplit(F1$text, "_"))
## now cbind() to the data frame
F1 <- cbind(F1, matrix(z, ncol = 2, byrow = TRUE))
F1

  ID1 ID2   text    1  2
1  A1  B1 NONE_. NONE  .
2  A1  B1  cf_12   cf 12
3  A1  B1 NONE_. NONE  .
4  A2  B2  X2_25   X2 25
5  A2  B3  fd_15   fd 15

## You can change the names of the 2 columns yourself

Cheers,
Bert

Bert Gunter

"The trouble with having an open mind is that people keep coming along

and sticking things into it."

-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )


On Tue, Sep 22, 2020 at 12:19 PM Rui Barradas <ruipbarradas at sapo.pt>

wrote:

Hello,

A base R solution with strsplit, like in your code.

F1$Y1 <- +grepl("_", F1$text)

tmp <- strsplit(as.character(F1$text), "_")
tmp <- lapply(tmp, function(x) if(length(x) == 1) c(x, ".") else x)
tmp <- do.call(rbind, tmp)
colnames(tmp) <- c("X1", "X2")
F1 <- cbind(F1[-3], tmp)    # remove the original column
rm(tmp)

F1
#  ID1 ID2 Y1   X1 X2
#1  A1  B1  0 NONE  .
#2  A1  B1  1   cf 12
#3  A1  B1  0 NONE  .
#4  A2  B2  1   X2 25
#5  A2  B3  1   fd 15


Note that cbind dispatches on F1, an object of class "data.frame".
Therefore it's the method cbind.data.frame that is called and the result
is also a df, though tmp is a "matrix".


Hope this helps,

Rui Barradas


?s 20:07 de 22/09/20, Rui Barradas escreveu:

Hello,

Something like this?


F1$Y1 <- +grepl("_", F1$text)
F1 <- F1[c(1, 2, 4, 3)]
F1 <- tidyr::separate(F1, text, into = c("X1", "X2"), sep = "_", fill

=

"right")
F1


Hope this helps,

Rui Barradas

?s 19:55 de 22/09/20, Val escreveu:

HI All,

I am trying to create   new columns based on another column string
content. First I want to identify rows that contain a particular
string.  If it contains, I want to split the string and create two
variables.

Here is my sample of data.
F1<-read.table(text="ID1  ID2  text
A1 B1   NONE
A1 B1   cf_12
A1 B1   NONE
A2 B2   X2_25
A2 B3   fd_15  ",header=TRUE,stringsAsFactors=F)
If the variable "text" contains this "_" I want to create an

indicator

variable as shown below

F1$Y1 <- ifelse(grepl("_", F1$text),1,0)


Then I want to split that string in to two, before "_" and after "_"
and create two variables as shown below
x1= strsplit(as.character(F1$text),'_',2)

My problem is how to combine this with the original data frame. The
desired  output is shown   below,


ID1 ID2  Y1   X1    X2
A1  B1    0   NONE   .
A1  B1   1    cf        12
A1  B1   0  NONE   .
A2  B2   1    X2    25
A2  B3   1    fd    15

Any help?
Thank you.