Hi I'm not sure how to ask this, but its a very easy question to answer for
an R person.
What is an easy way to check for a column value and then assigne a new
column a value based on that old column value?
For example, Im doing
colordata <- data.frame(id = c(1,2,3,4,5), color = c("blue",
"red",
"green", "blue", "orange"))
for (i in 1:nrow(colordata)){
colordata$response[i] <- ifelse(colordata[i,"color"] ==
"blue", 1, 0)
}
which works, but I don't want to use the for loop I want to
"vecotrize"
this. How would this be implemented?
[[alternative HTML version deleted]]
ifelse is vectorised, so just use that without the loop. colordata$response <- ifelse(colordata$color == 'blue', 1, 0) David On 7 April 2016 at 12:41, Michael Artz <michaeleartz at gmail.com> wrote:> Hi I'm not sure how to ask this, but its a very easy question to answer for > an R person. > > What is an easy way to check for a column value and then assigne a new > column a value based on that old column value? > > For example, Im doing > colordata <- data.frame(id = c(1,2,3,4,5), color = c("blue", "red", > "green", "blue", "orange")) > for (i in 1:nrow(colordata)){ > colordata$response[i] <- ifelse(colordata[i,"color"] == "blue", 1, 0) > } > > which works, but I don't want to use the for loop I want to "vecotrize" > this. How would this be implemented? > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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]]
Thaks so much! And how would you incorporate lapply() here? On Thu, Apr 7, 2016 at 6:52 AM, David Barron <dnbarron at gmail.com> wrote:> ifelse is vectorised, so just use that without the loop. > > colordata$response <- ifelse(colordata$color == 'blue', 1, 0) > > David > > On 7 April 2016 at 12:41, Michael Artz <michaeleartz at gmail.com> wrote: > >> Hi I'm not sure how to ask this, but its a very easy question to answer >> for >> an R person. >> >> What is an easy way to check for a column value and then assigne a new >> column a value based on that old column value? >> >> For example, Im doing >> colordata <- data.frame(id = c(1,2,3,4,5), color = c("blue", "red", >> "green", "blue", "orange")) >> for (i in 1:nrow(colordata)){ >> colordata$response[i] <- ifelse(colordata[i,"color"] == "blue", 1, 0) >> } >> >> which works, but I don't want to use the for loop I want to "vecotrize" >> this. How would this be implemented? >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide >> http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. >> > >[[alternative HTML version deleted]]
== is also vectorised, and you're better off with TRUE and FALSE rather than 1 and 0, so I'd recommend: colordata$response <- colordata$color == 'blue' Hadley On Thu, Apr 7, 2016 at 6:52 AM, David Barron <dnbarron at gmail.com> wrote:> ifelse is vectorised, so just use that without the loop. > > colordata$response <- ifelse(colordata$color == 'blue', 1, 0) > > David > > On 7 April 2016 at 12:41, Michael Artz <michaeleartz at gmail.com> wrote: > >> Hi I'm not sure how to ask this, but its a very easy question to answer for >> an R person. >> >> What is an easy way to check for a column value and then assigne a new >> column a value based on that old column value? >> >> For example, Im doing >> colordata <- data.frame(id = c(1,2,3,4,5), color = c("blue", "red", >> "green", "blue", "orange")) >> for (i in 1:nrow(colordata)){ >> colordata$response[i] <- ifelse(colordata[i,"color"] == "blue", 1, 0) >> } >> >> which works, but I don't want to use the for loop I want to "vecotrize" >> this. How would this be implemented? >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see >> 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]] > > ______________________________________________ > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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.-- http://hadley.nz
ruipbarradas at sapo.pt
2016-Apr-07 13:43 UTC
[R] simple question on data frames assignment
Hello, Or even simpler, without ifelse, colordata$response <- colordata$color == 'blue' + 0 Hope this helps, Rui Barradas ? Citando David Barron <dnbarron at gmail.com>:> ifelse is vectorised, so just use that without the loop. > > colordata$response <- ifelse(colordata$color == 'blue', 1, 0) > > David > > On 7 April 2016 at 12:41, Michael Artz <michaeleartz at gmail.com> wrote: >> Hi I'm not sure how to ask this, but its a very easy question to answer for >> an R person. >> >> What is an easy way to check for a column value and then assigne a new >> column a value based on that old column value? >> >> For example, Im doing >> colordata <- data.frame(id = c(1,2,3,4,5), color = c("blue", "red", >> "green", "blue", "orange")) >> for (i in 1:nrow(colordata)){ >> ? ?colordata$response[i] <- ifelse(colordata[i,"color"] == "blue", 1, 0) >> } >> >> which works,? but I don't want to use the for loop I want to "vecotrize" >> this.? How would this be implemented? >> >> ? ? ? ? [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see >> 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]] > > ______________________________________________ > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.htmland provide commented, > minimal, self-contained, reproducible code.? [[alternative HTML version deleted]]