Hi R-Users,
I wrote a simple function to change values of a matrix or vector to NA
based on the element value being -9999 or -999999. I don't understand
why the function returns a unit vector (NA) instead of setting all
values in the vector which have -9999 or -999999 to NA. When I apply the
function in line, it appears to work correctly?
Can someone enlighten me what I am doing wrong?
Thanks in advance.
David
Here's my example:
ConvertMissingToNA <- function (values) {
return ( values[ values == -9999 | values == -999999] <- NA )
}
d <- floor(runif(10, 1, 100))
pos <- floor (runif(5, 1, 10))
d[pos] <- -9999
pos <- floor (runif(2, 1, 10))
d[pos] <- -999999
print (d)
# now apply function
e <- ConvertMissingToNA (d) # will return NA as a unit vector
print (e)
# conduct function in-line
d[ d == -9999 | d == -999999] <- NA # correctly converts values to NA
print (d)
Unexpected returned value from a function
5 messages · Hutchinson,David [PYR], jim holtman, Dan Davison +1 more
try this -- you have to return the entire vector:
ConvertMissingToNA <- function (values) {
values[ values == -9999 | values == -999999] <- NA
values
}
d <- floor(runif(10, 1, 100))
pos <- floor (runif(5, 1, 10))
d[pos] <- -9999
pos <- floor (runif(2, 1, 10))
d[pos] <- -999999
print (d)
# now apply function
e <- ConvertMissingToNA (d) # will return NA as a unit vector
print (e)
# conduct function in-line
d[ d == -9999 | d == -999999] <- NA # correctly converts values to NA
print (d)
On Tue, Sep 16, 2008 at 6:19 PM, Hutchinson,David [PYR]
<David.Hutchinson at ec.gc.ca> wrote:
Hi R-Users,
I wrote a simple function to change values of a matrix or vector to NA
based on the element value being -9999 or -999999. I don't understand
why the function returns a unit vector (NA) instead of setting all
values in the vector which have -9999 or -999999 to NA. When I apply the
function in line, it appears to work correctly?
Can someone enlighten me what I am doing wrong?
Thanks in advance.
David
Here's my example:
ConvertMissingToNA <- function (values) {
return ( values[ values == -9999 | values == -999999] <- NA )
}
d <- floor(runif(10, 1, 100))
pos <- floor (runif(5, 1, 10))
d[pos] <- -9999
pos <- floor (runif(2, 1, 10))
d[pos] <- -999999
print (d)
# now apply function
e <- ConvertMissingToNA (d) # will return NA as a unit vector
print (e)
# conduct function in-line
d[ d == -9999 | d == -999999] <- NA # correctly converts values to NA
print (d)
______________________________________________ R-help at r-project.org 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 that you are trying to solve?
Quoting "Hutchinson,David [PYR]" <David.Hutchinson at ec.gc.ca>:
I wrote a simple function to change values of a matrix or vector to NA based on the element value being -9999 or -999999. I don't understand why the function returns a unit vector (NA) instead of setting all values in the vector which have -9999 or -999999 to NA. When I apply the function in line, it appears to work correctly? Can someone enlighten me what I am doing wrong?
return ( values[ values == -9999 | values == -999999] <- NA )
the assignment itself evaluates to the assigned value, in this case NA; that's what your function returns. Check this:
foo <- (a <- 3) a
[1] 3
foo
[1] 3
foo <- (a <- NA) a
[1] NA
foo
[1] NA
this way your function should work as intended:
ConvertMissingToNA <- function(values)
{
values[ values == -9999 | values == -999999] <- NA
return values
}
Peter
What you want is
ConvertMissingToNA <- function (values) {
values[ values == -9999 | values == -999999] <- NA
return( values )
}
To see why your version doesn't do what you wanted, maybe it helps to
consider the following?
x <- 1:10
y <- (x[3:6] <- 99)
y ## 99
(It's perhaps not entirely obvious that the value of y should be 99
and not c(99,99,99,99), but anyway, neither correspond to what you
wanted.)
Dan
On Tue, Sep 16, 2008 at 03:19:53PM -0700, Hutchinson,David [PYR] wrote:
Hi R-Users,
I wrote a simple function to change values of a matrix or vector to NA
based on the element value being -9999 or -999999. I don't understand
why the function returns a unit vector (NA) instead of setting all
values in the vector which have -9999 or -999999 to NA. When I apply the
function in line, it appears to work correctly?
Can someone enlighten me what I am doing wrong?
Thanks in advance.
David
Here's my example:
ConvertMissingToNA <- function (values) {
return ( values[ values == -9999 | values == -999999] <- NA )
}
d <- floor(runif(10, 1, 100))
pos <- floor (runif(5, 1, 10))
d[pos] <- -9999
pos <- floor (runif(2, 1, 10))
d[pos] <- -999999
print (d)
# now apply function
e <- ConvertMissingToNA (d) # will return NA as a unit vector
print (e)
# conduct function in-line
d[ d == -9999 | d == -999999] <- NA # correctly converts values to NA
print (d)
______________________________________________ R-help at r-project.org 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.
Sorry, there was a stupid cut & paste mistake (missing parentheses in
return statement...)
ConvertMissingToNA <- function(values)
{
values[values == -9999 | values == -999999] <- NA
return(values)
}
Peter