[R] Equivalents of Matlab's 'find' and 'end'

[Gavin Simpson]

Bryan L. Brown wrote:
> Sorry if these questions have been asked recently--I'm new to this
> list.

Hi Bryan,

A useful resource is Robin Hankin's contributed document "R and Octave":

http://cran.r-project.org/doc/contrib/R-and-octave-2.txt


> The first is Matlab's 'find' command. This is one of the most useful
> commands in Matab.  Basically, if X is the vector
> 
> X=[3, 2, 1, 1, 2, 3]
> 
> the command
> 
> 'find(X==1)'
> 
> would return the vector [3, 4] 

 > x <- c(3, 2, 1, 1, 2, 3)
 > which(x == 1)
[1] 3 4


> 
> The second Matlab command that I'd like to find an R equivalent for
> is 'end'.  'end' is just a simple little command that indicates the
> end of a row/column.  It is incredibly handy when used to subset
> matrices like
> 
> Y = X(2:end)
> 
> and produces Y=[2, 1, 1, 2, 3] if the X is the same as in the
> previous example. 

 > Y <- x[-1]
 > Y
[1] 2 1 1 2 3

Not quite the same I'll grant you, but results in the same thing. If you 
wanted Y = X(4:end) you could use:

 > Y <- x[-c(1:3)]
 > Y
[1] 1 2 3

HTH

Gav
-- 
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Gavin Simpson                     [T] +44 (0)20 7679 5522
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