R help - Nov 2016 - using grepl in dplyr

Hello All,

I have a dataframe of about 1.5 million rows from this dataframe I need to
filter out identifiers. ?An example would be 070000-07099, AD0000-AD0999, and
AL0000-AL9999, FN0000-FN9999. ?I am using grepl to identify those of interest as
follows:

?grepl("^[FN]|[AD]{2}", Identifier)

The above seems to work in the case of FN and AD. ?However, there are 20 such
identifiers and there must be a better way to do this than a long "or"
statement. ?Ultimately, I would like to filter these out using dplyr which I
think the first step is to create a vector of TRUE/FALSE then filter on TRUE

Any Ideas are appreciated,
Glenn

That is not a very selective regex.

Actually, a long "or" probably is best, but you don't have to type
it in directly.

prefixes <- c( "AD", "FN" )
pat <- paste0( "^(", paste( prefixes, collapse="|" ),
")[0-9]{4}$" )
grepl( pat, Identifier )

-- 
Sent from my phone. Please excuse my brevity.

On November 29, 2016 10:37:29 AM PST, Glenn Schultz <glennmschultz at
me.com> wrote:
>Hello All,
>
>I have a dataframe of about 1.5 million rows from this dataframe I need
>to filter out identifiers. ?An example would be 070000-07099,
>AD0000-AD0999, and AL0000-AL9999, FN0000-FN9999. ?I am using grepl to
>identify those of interest as follows:
>
>?grepl("^[FN]|[AD]{2}", Identifier)
>
>The above seems to work in the case of FN and AD. ?However, there are
>20 such identifiers and there must be a better way to do this than a
>long "or" statement. ?Ultimately, I would like to filter these out
>using dplyr which I think the first step is to create a vector of
>TRUE/FALSE then filter on TRUE
>
>Any Ideas are appreciated,
>Glenn
>
>
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