[R] subsetting a data frame using string matching

[Chuck Cleland]

On 1/21/2008 5:18 AM, Karin Lagesen wrote:
> Example data frame: 
> 
> 
> a = c("Alpha", "Beta", "Gamma", "Beeta", "Alpha", "beta")
> b = c(1:6)
> example = data.frame("Title" = a, "Vals" = b)
> 
> 
>> example
>   Title Vals
> 1 Alpha    1
> 2  Beta    2
> 3 Gamma    3
> 4 Beeta    4
> 5 Alpha    5
> 6  beta    6
> 
> I would like to be able to get a new data frame from this data frame
> containing only rows that match a certain string. In this case it
> could for instance be the string "eta". I have tried various ways of
> using agrep and grep, but so far I have not found anything that
> worked.
> 
> Thankyou in advance for your help!

a <- c("Alpha", "Beta", "Gamma", "Beeta", "Alpha", "beta")
b <- c(1:6)
df <- data.frame(Title = a, Vals = b)
df[grep("eta", df$Title),]
   Title Vals
2  Beta    2
4 Beeta    4
6  beta    6

> Karin

-- 
Chuck Cleland, Ph.D.
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