Testing if all elements are equal in a vector/matrix

or perhaps

length(unique(x))==1



-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Patrick Burns
Sent: Monday, August 29, 2005 5:22 PM
To: vincent.goulet at act.ulaval.ca
Cc: r-help at stat.math.ethz.ch
Subject: Re: [R] Testing if all elements are equal in a vector/matrix

How about

diff(range(x)) < tolerance

Patrick Burns
patrick at burns-stat.com
+44 (0)20 8525 0696
http://www.burns-stat.com
(home of S Poetry and "A Guide for the Unwilling S User")

Is there a canonical way to check if all elements of a vector or matrix

are the same? Solutions below work, but look hackish to me.

 

x <- rep(1, 10)
all(x == x[1])  # == operator does not provide for small differences
   

[1] TRUE
 

isTRUE(all.equal(x, rep(x[1], length(x)))) # ugly
   

[1] TRUE

Best,

Vincent
 

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