& and |
There are & and | operators in the R language.
There is an | operator in regular expressions.
There is NOT any & operator in regular expressions.
grep("ConfoMap&GuineaPigs", mydata, value=TRUE)
looks for elements of mydata containing the literal
string 'ConfoMap&GuineaPigs'.
foo <- c("a","b","cab","back")
foo[grepl("a",foo) & grepl("b",foo)]
[1] "cab" "back" grepl returns a TRUE/FALSE vector.
On Thu, 20 Aug 2020 at 02:53, Ivan Calandra <calandra at rgzm.de> wrote:
Dear useRs,
I feel really stupid, but I cannot understand why "&" doesn't work as I
expect, while "|" does.
I have the following vector:
mydata <- c("SSFA-ConfoMap_GuineaPigs_NMPfilled.csv",
"SSFA-ConfoMap_Lithics_NMPfilled.csv",
"SSFA-ConfoMap_Sheeps_NMPfilled.csv", "SSFA-Toothfrax_GuineaPigs.xlsx",
"SSFA-Toothfrax_Lithics.xlsx", "SSFA-Toothfrax_Sheeps.xlsx")
and I want to find the values that include both "ConfoMap" and
"GuineaPigs".
If I do:
grep("ConfoMap&GuineaPigs", mydata, value=TRUE)
it returns an empty vector, character(0).
But if I do:
grep("ConfoMap|GuineaPigs", mydata, value=TRUE)
it returns all the elements that include either "ConfoMap" or
"GuineaPigs", as I would expect.
So what is wrong with my "&" construct? How can I return the elements
that include both parts?
Thank you for your help!
Ivan
--
Dr. Ivan Calandra
TraCEr, laboratory for Traceology and Controlled Experiments
MONREPOS Archaeological Research Centre and
Museum for Human Behavioural Evolution
Schloss Monrepos
56567 Neuwied, Germany
+49 (0) 2631 9772-243
https://www.researchgate.net/profile/Ivan_Calandra
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