R help - Jan 2007 - simple q: returning a logical vector of substring matches

I'm a relative R novice, and sometimes the simple things trip me up.

Suppose I have

a <- c("apple", "pear")

and I want a logical vector of whether each of these strings contains  
"ear" (in this case, F T). What is the idiom?

Quizzically,
Mark Lindeman

On Sat, 2007-01-20 at 13:30 -0500, lindeman at bard.edu
wrote:
> I'm a relative R novice, and sometimes the simple things trip me up.
> 
> Suppose I have
> 
> a <- c("apple", "pear")
> 
> and I want a logical vector of whether each of these strings contains  
> "ear" (in this case, F T). What is the idiom?
> 
> Quizzically,
> Mark Lindeman
See ?grep and ?regexp

a <- c("apple", "pear")
> grep("ear", a)
[1] 2
> grep("ear", a, value = TRUE)
[1] "pear"

If you actually want the answer to be FALSE TRUE, then:
> a %in% grep("ear", a, value = TRUE)
[1] FALSE  TRUE

In that case see ?"%in%"

HTH,

Marc Schwartz

You can try the following:

 a == grep("ear", a, value=T)

-Christos

Christos Hatzis, Ph.D.
Nuvera Biosciences, Inc.
400 West Cummings Park
Suite 5350
Woburn, MA 01801
Tel: 781-938-3830
www.nuverabio.com
 
 

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of lindeman at bard.edu
Sent: Saturday, January 20, 2007 1:31 PM
To: r-help at stat.math.ethz.ch
Subject: [R] simple q: returning a logical vector of substring matches

I'm a relative R novice, and sometimes the simple things trip me up.

Suppose I have

a <- c("apple", "pear")

and I want a logical vector of whether each of these strings contains
"ear"
(in this case, F T). What is the idiom?

Quizzically,
Mark Lindeman

______________________________________________
R-help at stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

try  'regexpr'
> a <- c("apple", "pear")
> regexpr('ear',a)!=-1
[1] FALSE  TRUE
>


On 1/20/07, lindeman@bard.edu <lindeman@bard.edu>
wrote:
>
> I'm a relative R novice, and sometimes the simple things trip me up.
>
> Suppose I have
>
> a <- c("apple", "pear")
>
> and I want a logical vector of whether each of these strings contains
> "ear" (in this case, F T). What is the idiom?
>
> Quizzically,
> Mark Lindeman
>
> ______________________________________________
> R-help@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?

	[[alternative HTML version deleted]]

Using the builtin month.abb try this:

  regexpr("ov", month.abb) > 0

Although not needed here, if "ov" were a character string that could
have
special characters such as . and * that have special meaning in a regular
expression then do this to prevent such interpretation:

  regexpr("ov", month.abb, fixed = TRUE) > 0

See ?regexpr


On 1/20/07, lindeman at bard.edu <lindeman at bard.edu>
wrote:
> I'm a relative R novice, and sometimes the simple things trip me up.
>
> Suppose I have
>
> a <- c("apple", "pear")
>
> and I want a logical vector of whether each of these strings contains
> "ear" (in this case, F T). What is the idiom?
>
> Quizzically,
> Mark Lindeman
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>