Greetings
I have a bunch of NAs in a column of categorical variables designating
the size classes (e.g., smallest to largest: 1,2,3,4) of cave crickets.
I'd like to substitute "U" (for unknown) for the NAs. Can anyone
give me
an idea how to do this? Thanks in advance.
Cheers
Kurt
***************************************************************
Kurt Lewis Helf, Ph.D.
Ecologist
EEO Counselor
National Park Service
Cumberland Piedmont Network
P.O. Box 8
Mammoth Cave, KY 42259
Ph: 270-758-2163
Lab: 270-758-2151
Fax: 270-758-2609
****************************************************************
Science, in constantly seeking real explanations, reveals the true majesty
of our world in all its complexity.
-Richard Dawkins
The scientific tradition is distinguished from the pre-scientific tradition
in having two layers. Like the latter it passes on its theories but it
also passes on a critical attitude towards them. The theories are passed
on not as dogmas but rather with the challenge to discuss them and improve
upon them.
-Karl Popper
...consider yourself a guest in the home of other creatures as significant
as yourself.
-Wayside at Wilderness Threshold in McKittrick Canyon, Guadalupe Mountains
National Park, TX
Cumberland Piedmont Network (CUPN) Homepage:
http://tiny.cc/e7cdx
CUPN Forest Pest Monitoring Website:
http://bit.ly/9rhUZQ
CUPN Cave Cricket Monitoring Website:
http://tiny.cc/ntcql
CUPN Cave Aquatic Biota Monitoring Website:
http://tiny.cc/n2z1o
Well, (have you read "An Intro to R," which I think might have enabled you to figure this out for yourself?).... Convert the factor to character, use is.na() to substitute, convert back to factor. e.g.> z <- factor (c(1,2,3,NA)) > z<- as.character(z) > z[is.na(z)] <- "U" > factor(z)[1] 1 2 3 U Levels: 1 2 3 U HOWEVER, this is almost certainly a BAD IDEA, as you have now essentially lost the ordering of the levels, which is important information for modeling. In general, R handles NA's (perhaps not always gracefully) and you should leave them as such and let R do its job. A lot of effort by wise folks has been expended to make this possible. Cheers, Bert On Tue, Jan 18, 2011 at 2:25 PM, <Kurt_Helf at nps.gov> wrote:> Greetings > ? ? I have a bunch of NAs in a column of categorical variables designating > the size classes (e.g., smallest to largest: 1,2,3,4) of cave crickets. > I'd like to substitute "U" (for unknown) for the NAs. ?Can anyone give me > an idea how to do this? ?Thanks in advance. > Cheers > Kurt > > *************************************************************** > Kurt Lewis Helf, Ph.D. > Ecologist > EEO Counselor > National Park Service > Cumberland Piedmont Network > P.O. Box 8 > Mammoth Cave, KY 42259 > Ph: 270-758-2163 > Lab: 270-758-2151 > Fax: 270-758-2609 > **************************************************************** > Science, in constantly seeking real explanations, reveals the true majesty > of our world in all its complexity. > -Richard Dawkins > > The scientific tradition is distinguished from the pre-scientific tradition > in having two layers. ?Like the latter it passes on its theories but it > also passes on a critical attitude towards them. ?The theories are passed > on not as dogmas but rather with the challenge to discuss them and improve > upon them. > -Karl Popper > > ...consider yourself a guest in the home of other creatures as significant > as yourself. > -Wayside at Wilderness Threshold in McKittrick Canyon, Guadalupe Mountains > National Park, TX > > Cumberland Piedmont Network (CUPN) Homepage: > http://tiny.cc/e7cdx > > CUPN Forest Pest Monitoring Website: > http://bit.ly/9rhUZQ > > CUPN Cave Cricket Monitoring Website: > http://tiny.cc/ntcql > > CUPN Cave Aquatic Biota Monitoring Website: > http://tiny.cc/n2z1o > > ______________________________________________ > 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. >-- Bert Gunter Genentech Nonclinical Biostatistics
On Jan 18, 2011, at 5:25 PM, Kurt_Helf at nps.gov wrote:> Greetings > I have a bunch of NAs in a column of categorical variables > designating > the size classes (e.g., smallest to largest: 1,2,3,4) of cave > crickets. > I'd like to substitute "U" (for unknown) for the NAs. Can anyone > give me > an idea how to do this? Thanks in advance.> vect=factor(c(1,2,3,4,NA)) > vect [1] 1 2 3 4 <NA> Levels: 1 2 3 4 > levels(vect) <- c(levels(vect), "U") > vect[is.na(vect)] <- "U" > > vect [1] 1 2 3 4 U Levels: 1 2 3 4 U -- David.> Cheers > Kurt > > *************************************************************** > Kurt Lewis Helf, Ph.D. > Ecologist > EEO Counselor > National Park Service > Cumberland Piedmont Network > P.O. Box 8 > Mammoth Cave, KY 42259 > Ph: 270-758-2163 > Lab: 270-758-2151 > Fax: 270-758-2609 > **************************************************************** > Science, in constantly seeking real explanations, reveals the true > majesty > of our world in all its complexity. > -Richard Dawkins > > The scientific tradition is distinguished from the pre-scientific > tradition > in having two layers. Like the latter it passes on its theories but > it > also passes on a critical attitude towards them. The theories are > passed > on not as dogmas but rather with the challenge to discuss them and > improve > upon them. > -Karl Popper > > ...consider yourself a guest in the home of other creatures as > significant > as yourself. > -Wayside at Wilderness Threshold in McKittrick Canyon, Guadalupe > Mountains > National Park, TX > > Cumberland Piedmont Network (CUPN) Homepage: > http://tiny.cc/e7cdx > > CUPN Forest Pest Monitoring Website: > http://bit.ly/9rhUZQ > > CUPN Cave Cricket Monitoring Website: > http://tiny.cc/ntcql > > CUPN Cave Aquatic Biota Monitoring Website: > http://tiny.cc/n2z1o > > ______________________________________________ > 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.David Winsemius, MD West Hartford, CT