& 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
<mailto: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