Hello,
I have tried several options and with large dataframes this one was the
fastest (in my tests, of the ones I have tried).
s1 <- sapply(tot, function(x) grep('^E10', x, value = TRUE))
Then unlist(s1).
A close second (15% slower) was
s2 <- tot[sapply(tot, function(x) grepl('^E10', x))]
grep/unlist was 3.7 times slower:
grep("^E10", unlist(tot), value = TRUE)
Hope this helps,
Rui Barradas
Às 20:24 de 15/05/20, Ana Marija escreveu:
Hello,
this command was running for more than 2 hours
grep("E10",tot,value=T)
and no output
and this command
df1 <- tot %>% filter_all(any_vars(grepl( '^E10', .)))
gave me a subset (a data frame) of tot where ^E10
what I need is just a vector or all values in tot which start with E10.
Thanks
Ana
On Fri, May 15, 2020 at 12:13 PM Jeff Newmiller
<jdnew...@dcn.davis.ca.us> wrote:
Read about regular expressions... they are extremely useful.
df1 <- tot %>% filter_all(any_vars(grepl( '^E10', .)))
It is bad form not to put spaces around the <- assignment.
On May 15, 2020 10:00:04 AM PDT, Ana Marija <sokovic.anamar...@gmail.com> wrote:
Hello,
I have a data frame:
dim(tot)
[1] 502536 1093
How would I extract from it all strings that start with E10?
I know how to extract all rows that contain with E10
df0<-tot %>% filter_all(any_vars(. %in% c('E10')))
dim(df0)
[1] 5105 1093
but I just need a vector of strings that start with E10...
it would look something like this:
[1] "E102" "E109" "E108" "E103" "E104" "E105" "E101" "E106" "E107"
Thanks
Ana
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