Hello all,
I have a fairly simple data manipulation question. Say I have a dataframe
like this:
dat <- as.data.frame(runif(7, 3, 5))
dat$cat <-
factor(c("1","4","13","1","4","13","13A"))
dat
runif(7, 3, 5) cat
1 3.880020 1
2 4.062800 4
3 4.828950 13
4 4.761850 1
5 4.716962 4
6 3.868348 13
7 3.420944 13A
Under the dat$cat variable the 13A value is an analytical replicate. For my
purposes I would like to drop all values that are not an integer (i.e. 13A)
from the dataframe. Can anyone recommend a way to drop all rows where the
cat value is a non-integer?
Sorry for the simple question and thanks in advance.
Sam
--
*****************************************************
Sam Albers
Geography Program
University of Northern British Columbia
3333 University Way
Prince George, British Columbia
Canada, V2N 4Z9
phone: 250 960-6777
*****************************************************
[[alternative HTML version deleted]]
On Nov 17, 2010, at 6:27 PM, Sam Albers wrote:> Hello all, > > I have a fairly simple data manipulation question. Say I have a > dataframe > like this: > > dat <- as.data.frame(runif(7, 3, 5)) > dat$cat <- factor(c("1","4","13","1","4","13","13A")) > > dat > runif(7, 3, 5) cat > 1 3.880020 1 > 2 4.062800 4 > 3 4.828950 13 > 4 4.761850 1 > 5 4.716962 4 > 6 3.868348 13 > 7 3.420944 13A > > Under the dat$cat variable the 13A value is an analytical replicate. > For my > purposes I would like to drop all values that are not an integer > (i.e. 13A) > from the dataframe. Can anyone recommend a way to drop all rows > where the > cat value is a non-integer?dat[!is.na(as.numeric(as.character(dat$cat))), ] (You do get a warning about coercion to NA's but that is a good sign since that is what we were trying to exclude in the first place.)> > Sorry for the simple question and thanks in advance. > > Sam > -- > ***************************************************** > Sam Albers > Geography Program > University of Northern British Columbia > 3333 University Way > Prince George, British Columbia > Canada, V2N 4Z9 > phone: 250 960-6777 > ***************************************************** > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code.David Winsemius, MD West Hartford, CT
On 17/11/2010 6:27 PM, Sam Albers wrote:> Hello all, > > I have a fairly simple data manipulation question. Say I have a dataframe > like this: > > dat<- as.data.frame(runif(7, 3, 5)) > dat$cat<- factor(c("1","4","13","1","4","13","13A")) > > dat > runif(7, 3, 5) cat > 1 3.880020 1 > 2 4.062800 4 > 3 4.828950 13 > 4 4.761850 1 > 5 4.716962 4 > 6 3.868348 13 > 7 3.420944 13A > > Under the dat$cat variable the 13A value is an analytical replicate. For my > purposes I would like to drop all values that are not an integer (i.e. 13A) > from the dataframe. Can anyone recommend a way to drop all rows where the > cat value is a non-integer?You can see if an entry is non-numeric using nonnumeric <- is.na( as.numeric( as.character(dat$cat) ) ) With the data in your example, that test would be good enough. If you'd also like to be able to rule out non-integers like 13.1, you could use the lines: value <- as.numeric( as.character(dat$cat) ) # get the numbers noninteger <- value %% 1 != 0 # see if there's a fractional part noninteger <- noninteger | is.na(noninteger) # get rid of the NA's from line 1 Once you have a logical vector indicating which rows to keep, use it to index: dat[!noninteger,] Duncan Murdoch