R help - Nov 2005 - (no subject)

Hi,

I have written the following function to check whether a vector has elements
satisfying monotonicity.

is.monotone <- function(vec, increase=T){
# check for monotonicity in time-stamp data for cortisol collection
ans <- TRUE
vec.nomis <- vec[!is.na(vec)]
if (increase & any(diff(vec.nomis,1) < 0, na.rm=T)) ans <- FALSE
if (!increase & any(diff(vec.nomis,1) > 0, na.rm=T)) ans <- FALSE
ans
}

This works correctly, but I get this error message as below.
> x <- 2:10
> is.monotone(x)
[1] TRUE
Warning messages:
1: the condition has length > 1 and only the first element will be used in:
if (increase & any(diff(vec.nomis, 1) < 0, na.rm = T)) ans <- FALSE 
2: the condition has length > 1 and only the first element will be used in:
if (!increase & any(diff(vec.nomis, 1) > 0, na.rm = T)) ans <- FALSE
>
I am unable to see why the condition should have a length greater than 1,
since "any" should give me a single logical value.  

Can any one tell me what is going on here?  ( I am using version 2.1.1 on
Windows).

Thanks very much,
Ravi.

--------------------------------------------------------------------------
Ravi Varadhan, Ph.D.
Assistant Professor,?? The Center on Aging and Health
Division of Geriatric Medicine and Gerontology
Johns Hopkins University
Ph: (410) 502-2619
Fax: (410) 614-9625
Email:?? rvaradhan at jhmi.edu

Ravi Varadhan <RVARADHAN at jhmi.edu> writes:
> Hi,
> 
> I have written the following function to check whether a vector has
elements
> satisfying monotonicity.
> 
> is.monotone <- function(vec, increase=T){
> # check for monotonicity in time-stamp data for cortisol collection
> ans <- TRUE
> vec.nomis <- vec[!is.na(vec)]
> if (increase & any(diff(vec.nomis,1) < 0, na.rm=T)) ans <- FALSE
> if (!increase & any(diff(vec.nomis,1) > 0, na.rm=T)) ans <- FALSE
> ans
> }
> 
> This works correctly, but I get this error message as below.
> 
> > x <- 2:10
> > is.monotone(x)
> [1] TRUE
> Warning messages:
> 1: the condition has length > 1 and only the first element will be used
in:
> if (increase & any(diff(vec.nomis, 1) < 0, na.rm = T)) ans <-
FALSE
> 2: the condition has length > 1 and only the first element will be used
in:
> if (!increase & any(diff(vec.nomis, 1) > 0, na.rm = T)) ans <-
FALSE
> >
> 
> I am unable to see why the condition should have a length greater than 1,
> since "any" should give me a single logical value.  
> 
> Can any one tell me what is going on here?  ( I am using version 2.1.1 on
> Windows).
Would you happen to have a variable called "T" around?

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