I am sure this is a very basic question:
I have 600,000 categorical variables in a data.frame - each of which is classified as "0", "1", or "2" What I would like to do is collapse "1" and "2" and leave "0" by itself, such that after re-categorizing "0" = "0"; "1" = "1" and "2" = "1" --- in the end I only want "0" and "1" as categories for each of the variables. Also, if possible I would rather not create 600,000 new variables, if I can replace the existing variables with the new values that would be great! What would be the best way to do this? Thank you! -- Thanks, CC [[alternative HTML version deleted]] ______________________________________________ [hidden email] 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. |
Do you want to replace specific values of a data set?
df <- sample(c(0,1,2),600,replace=T) table(df) df[df==2]<-1 table(df) |
In reply to this post by CocaCola
Hi:
See ? levels. Here's a toy example: > x <- factor(sample(0:2, 10, replace = TRUE)) > x [1] 1 2 1 0 2 2 2 2 2 1 Levels: 0 1 2 > levels(x) <- c(0, 1, 1) # Change level 2 to 1 > x [1] 1 1 1 0 1 1 1 1 1 1 Levels: 0 1 HTH, Dennis On Fri, Jul 16, 2010 at 10:18 AM, CC <[hidden email]> wrote: > I am sure this is a very basic question: > > I have 600,000 categorical variables in a data.frame - each of which is > classified as "0", "1", or "2" > > What I would like to do is collapse "1" and "2" and leave "0" by itself, > such that after re-categorizing "0" = "0"; "1" = "1" and "2" = "1" --- in > the end I only want "0" and "1" as categories for each of the variables. > > Also, if possible I would rather not create 600,000 new variables, if I can > replace the existing variables with the new values that would be great! > > What would be the best way to do this? > > Thank you! > > > -- > Thanks, > CC > > [[alternative HTML version deleted]] > > ______________________________________________ > [hidden email] 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. > [[alternative HTML version deleted]] ______________________________________________ [hidden email] 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. |
In reply to this post by CocaCola
Hi,
On Fri, Jul 16, 2010 at 5:18 PM, CC <[hidden email]> wrote: > I am sure this is a very basic question: > > I have 600,000 categorical variables in a data.frame - each of which is > classified as "0", "1", or "2" > > What I would like to do is collapse "1" and "2" and leave "0" by itself, > such that after re-categorizing "0" = "0"; "1" = "1" and "2" = "1" --- in > the end I only want "0" and "1" as categories for each of the variables. Something like this should work for (i in names(dat)) { dat[, i] <- factor(dat[, i], levels = c("0", "1", "2"), labels = c("0", "1", "1)) } -Ista > > Also, if possible I would rather not create 600,000 new variables, if I can > replace the existing variables with the new values that would be great! > > What would be the best way to do this? > > Thank you! > > > -- > Thanks, > CC > > [[alternative HTML version deleted]] > > ______________________________________________ > [hidden email] 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. > -- Ista Zahn Graduate student University of Rochester Department of Clinical and Social Psychology http://yourpsyche.org ______________________________________________ [hidden email] 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. |
Ista Zahn wrote:
> Hi, > On Fri, Jul 16, 2010 at 5:18 PM, CC <[hidden email]> wrote: >> I am sure this is a very basic question: >> >> I have 600,000 categorical variables in a data.frame - each of which is >> classified as "0", "1", or "2" >> >> What I would like to do is collapse "1" and "2" and leave "0" by itself, >> such that after re-categorizing "0" = "0"; "1" = "1" and "2" = "1" --- in >> the end I only want "0" and "1" as categories for each of the variables. > > Something like this should work > > for (i in names(dat)) { > dat[, i] <- factor(dat[, i], levels = c("0", "1", "2"), labels = > c("0", "1", "1)) > } Unfortunately, it won't: > d <- 0:2 > factor(d, levels=c(0,1,1)) [1] 0 1 <NA> Levels: 0 1 1 Warning message: In `levels<-`(`*tmp*`, value = c("0", "1", "1")) : duplicated levels will not be allowed in factors anymore This effect, I have been told, goes way back to design choices in S (that you can have repeated level names) plus compatibility ever since. It would make more sense if it behaved like d <- factor(d); levels(d) <- c(0,1,1) and maybe, some time in the future, it will. Meanwhile, the above is the workaround. (BTW, if there are 600000 variables, you probably don't want to iterate over their names, more likely "for(i in seq_along(dat))...") -- Peter Dalgaard Center for Statistics, Copenhagen Business School Phone: (+45)38153501 Email: [hidden email] Priv: [hidden email] ______________________________________________ [hidden email] 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. |
Please look at Peter Dalgaard's response a little more
carefully. There's a big difference between the levels= argument (which must be unique) and the labels= argument (which need not be). Here are two ways to do what you want: > d = 0:2 > factor(d,levels=0:2,labels=c('0','1','1')) [1] 0 1 1 > library(car) > recode(d,"c(1,2)='1'") [1] 0 1 1 - Phil Spector Statistical Computing Facility Department of Statistics UC Berkeley [hidden email] On Sat, 17 Jul 2010, Peter Dalgaard wrote: > Ista Zahn wrote: >> Hi, >> On Fri, Jul 16, 2010 at 5:18 PM, CC <[hidden email]> wrote: >>> I am sure this is a very basic question: >>> >>> I have 600,000 categorical variables in a data.frame - each of which is >>> classified as "0", "1", or "2" >>> >>> What I would like to do is collapse "1" and "2" and leave "0" by itself, >>> such that after re-categorizing "0" = "0"; "1" = "1" and "2" = "1" --- in >>> the end I only want "0" and "1" as categories for each of the variables. >> >> Something like this should work >> >> for (i in names(dat)) { >> dat[, i] <- factor(dat[, i], levels = c("0", "1", "2"), labels = >> c("0", "1", "1)) >> } > > Unfortunately, it won't: > >> d <- 0:2 >> factor(d, levels=c(0,1,1)) > [1] 0 1 <NA> > Levels: 0 1 1 > Warning message: > In `levels<-`(`*tmp*`, value = c("0", "1", "1")) : > duplicated levels will not be allowed in factors anymore > > > This effect, I have been told, goes way back to design choices in S > (that you can have repeated level names) plus compatibility ever since. > > It would make more sense if it behaved like > > d <- factor(d); levels(d) <- c(0,1,1) > > and maybe, some time in the future, it will. Meanwhile, the above is the > workaround. > > (BTW, if there are 600000 variables, you probably don't want to iterate > over their names, more likely "for(i in seq_along(dat))...") > > -- > Peter Dalgaard > Center for Statistics, Copenhagen Business School > Phone: (+45)38153501 > Email: [hidden email] Priv: [hidden email] > > ______________________________________________ > [hidden email] 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. > ______________________________________________ [hidden email] 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. |
In reply to this post by Peter Dalgaard-2
On Sat, Jul 17, 2010 at 9:03 PM, Peter Dalgaard <[hidden email]> wrote:
> Ista Zahn wrote: >> Hi, >> On Fri, Jul 16, 2010 at 5:18 PM, CC <[hidden email]> wrote: >>> I am sure this is a very basic question: >>> >>> I have 600,000 categorical variables in a data.frame - each of which is >>> classified as "0", "1", or "2" >>> >>> What I would like to do is collapse "1" and "2" and leave "0" by itself, >>> such that after re-categorizing "0" = "0"; "1" = "1" and "2" = "1" --- in >>> the end I only want "0" and "1" as categories for each of the variables. >> >> Something like this should work >> >> for (i in names(dat)) { >> dat[, i] <- factor(dat[, i], levels = c("0", "1", "2"), labels = >> c("0", "1", "1)) >> } > > Unfortunately, it won't: > >> d <- 0:2 >> factor(d, levels=c(0,1,1)) > [1] 0 1 <NA> > Levels: 0 1 1 > Warning message: > In `levels<-`(`*tmp*`, value = c("0", "1", "1")) : > duplicated levels will not be allowed in factors anymore > I stand corrected. Thank you Peter. > > This effect, I have been told, goes way back to design choices in S > (that you can have repeated level names) plus compatibility ever since. > > It would make more sense if it behaved like > > d <- factor(d); levels(d) <- c(0,1,1) > > and maybe, some time in the future, it will. Meanwhile, the above is the > workaround. > > (BTW, if there are 600000 variables, you probably don't want to iterate > over their names, more likely "for(i in seq_along(dat))...") > > -- > Peter Dalgaard > Center for Statistics, Copenhagen Business School > Phone: (+45)38153501 > Email: [hidden email] Priv: [hidden email] > > ______________________________________________ > [hidden email] 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. > -- Ista Zahn Graduate student University of Rochester Department of Clinical and Social Psychology http://yourpsyche.org ______________________________________________ [hidden email] 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. |
In reply to this post by Peter Dalgaard-2
On 2010-07-17 23:03, Peter Dalgaard wrote:
> Ista Zahn wrote: >> Hi, >> On Fri, Jul 16, 2010 at 5:18 PM, CC <[hidden email]> wrote: >>> I am sure this is a very basic question: >>> >>> I have 600,000 categorical variables in a data.frame - each of which is >>> classified as "0", "1", or "2" >>> >>> What I would like to do is collapse "1" and "2" and leave "0" by itself, >>> such that after re-categorizing "0" = "0"; "1" = "1" and "2" = "1" --- in >>> the end I only want "0" and "1" as categories for each of the variables. >> Something like this should work >> >> for (i in names(dat)) { >> dat[, i] <- factor(dat[, i], levels = c("0", "1", "2"), labels = >> c("0", "1", "1)) >> } > > Unfortunately, it won't: > >> d <- 0:2 >> factor(d, levels=c(0,1,1)) > [1] 0 1 <NA> > Levels: 0 1 1 > Warning message: > In `levels<-`(`*tmp*`, value = c("0", "1", "1")) : > duplicated levels will not be allowed in factors anymore > > > This effect, I have been told, goes way back to design choices in S > (that you can have repeated level names) plus compatibility ever since. > > It would make more sense if it behaved like > > d <- factor(d); levels(d) <- c(0,1,1) > > and maybe, some time in the future, it will. Meanwhile, the above is the > workaround. > > (BTW, if there are 600000 variables, you probably don't want to iterate > over their names, more likely "for(i in seq_along(dat))...") You could also use 'lapply' with 'levels<-': > ### Example data > set.seed(1) > d <- 0:2 > DF <- data.frame(X1 = factor(sample(d, size = 10, replace = TRUE)), + X2 = factor(sample(d, size = 10, replace = TRUE))) > DF X1 X2 1 0 0 2 1 0 3 1 2 4 2 1 5 0 2 6 2 1 7 2 2 8 1 2 9 1 1 10 0 2 > > ### Reorder levels and replace > DF[] <- lapply(DF, function(x) "levels<-"(x, c("0", "1", "1"))) > DF X1 X2 1 0 0 2 1 0 3 1 1 4 1 1 5 0 1 6 1 1 7 1 1 8 1 1 9 1 1 10 0 1 HTH, Henric ______________________________________________ [hidden email] 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. |
In reply to this post by Phil Spector
Thank you very much to all of you for the responses!
Phil, the following two examples worked well in re-categorizing. Is there any way I can retain my original data.frame format? Once I re-categorize the data, the format becomes numeric and the original column names are not retained. I probably should have mentioned this earlier - I plan on using the re-categorized data for coxph using the surv() function. Here's how I am applying the re-categorization to my data: ***************************************************************************** library(survival) library(car) gg <- read.table("k.csv", header=TRUE, sep = ",") col = dim(genot)[2] for(i in 1:col) { aa<- recode(gg[,i], "c(1,2)='1'") } for(i in 1:col) { dd<-factor(gg[,i],levels=0:2,labels=c('0','1','1')) } Thanks, CC On Sat, Jul 17, 2010 at 2:15 PM, Phil Spector <[hidden email]>wrote: > Please look at Peter Dalgaard's response a little more > carefully. There's a big difference between the levels= > argument (which must be unique) and the labels= argument (which need not > be). Here are two ways > to do what you want: > > d = 0:2 >> factor(d,levels=0:2,labels=c('0','1','1')) >> > [1] 0 1 1 > >> library(car) >> recode(d,"c(1,2)='1'") >> > [1] 0 1 1 > > > - Phil Spector > Statistical Computing Facility > Department of Statistics > UC Berkeley > [hidden email] > > > > Thanks, CC [[alternative HTML version deleted]] ______________________________________________ [hidden email] 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. |
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