[R] how to get all strings in a data frame that start with a particular string
Rasmus Liland
jen@r@@mu@ @end|ng |rom gm@||@com
Fri Apr 10 19:00:48 CEST 2020
On 2020-04-10 11:15 -0500, Ana Marija wrote:
> I have a data frame (tot) with about
> 2000 columns. How can I extract from
> it all strings that start with E14?
>
> I tried this:
> e14 <- sapply(tot, function(x) grepl("^E14", x))
>
> but this returns me just TRUE and
> FALSE vector, how do I get actual
> strings that start with E14?
Dear Ana,
perhaps you thought of something along
the lines of this:
ncol <- 2000
nrow <- 3
line <-
c("a", "b",
"some text E14 bla bla some more text",
"d",
"E14 ... hey this starts and also ends with E14",
"E14 something-something",
"another string")
tot <-
as.data.frame(matrix(rep(line,
times=ncol*nrow),
ncol=ncol,
byrow=T))
# Now, tot is a df with some cells
# containing replicates of line, some
# cells there are now starting with E14
# ... so we need to convert it to a
# character matrix to be able to find
# the indecies of the cells starting
# with E14:
tot <- as.matrix(tot)
idx <- grepl("^E14", tot)
tot[idx]
Best,
Rasmus
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