CODEWITHSUNDEEP
rmatrixwildcard
y154707
y154707

Reputation: 93

Wildcard to match string in R

This might sound quite silly but it's driving me nuts. I have a matrix that has alphanumeric values and I'm struggling to test if some elements of that matrix match only the initial and final letters. As I don't care the middle character, I'm trying (withouth success) to use a wildcard.

As an example, consider this matrix:

m <- matrix(nrow=3,ncol=3)
m[1,]=c("NCF","NBB","FGF")
m[2,]=c("MCF","N2B","CCD")
m[3,]=c("A3B","N4F","MCP")

I want to evaluate if m[2,2] starts with "N" and ends with "B", regardless of the 2nd letter in the string. I've tried something like

grep("N.B",m)

and it works, but still I want to know if there is a more compact way of doing it, like:

m[2,2]="N.B"

which ovbiously didn't work!

Thanks

Upvotes: 2

Views: 929

Answers (1)

GKi
GKi

Reputation: 39657

You can use grepl with the subseted m like:

grepl("^N.B$", m[2,2])
#[1] TRUE

or use startsWith and endsWith:

startsWith(m[2,2], "N") & endsWith(m[2,2], "B")
#[1] TRUE

Upvotes: 1

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