if() command
On Wed, 14 Sep 2005, Carlos Mauricio Cardeal Mendes wrote:
Ok Petr, I run your suggestion and I got this message:
> age<-sample(seq(10,50,10), 20, replace=T)
>
> if (age <=10) {group <- 1} else if (age > 10 & age <= 20) {group <-
2} else {group <- 3}
Warning message:
the condition has length > 1 and only the first element will be used in:
if (age <= 10) {
What does it means ?
And when I look to the database I have no new classification !
Although the syntax issue is real, if() is not the way to go if you are comparing a vector with a scalar; if() will only compare the first element of the vector with the scalar. The ifelse() function is vectorised:
age<-sample(seq(10,50,10), 20, replace=T) group_ifelse <- ifelse(age > 10, ifelse(age > 20, 3, 2), 1) group_ifelse
[1] 3 2 3 3 3 2 3 3 1 2 3 1 1 1 3 2 3 2 3 3 or maybe even better, use the cut function to create a grouping factor:
group_cut <- cut(age, breaks=c(0,10,20,100), include.lowest=TRUE) group_cut
[1] (20,100] (10,20] (20,100] (20,100] (20,100] (10,20] (20,100] (20,100] [9] [0,10] (10,20] (20,100] [0,10] [0,10] [0,10] (20,100] (10,20] [17] (20,100] (10,20] (20,100] (20,100] Levels: [0,10] (10,20] (20,100]
age
[1] 30 20 30 40 30 20 50 50 10 20 30 10 10 10 30 20 40 20 50 40
as.integer(group_cut)
[1] 3 2 3 3 3 2 3 3 1 2 3 1 1 1 3 2 3 2 3 3 Sometimes you need to enclose cut() within ordered(), and if there are empty intervals, you may not get what you expect from the integer representation of the result. Yet another elegant function is findInterval():
group_findInterval <- findInterval(age, c(0,10.001,20.001,100)) group_findInterval
[1] 3 2 3 3 3 2 3 3 1 2 3 1 1 1 3 2 3 2 3 3 Hope this helps
Could you help please ? Mauricio Petr Pikal escreveu:
Hallo On 13 Sep 2005 at 10:29, Carlos Maur??cio Cardeal Mende wrote:
Hi everyone !
Could you please help me with this problem ?
I??ve trying to write a code that assign to a variable the content from
another, but all I??ve got is a message error. For example:
if (age <=10) {group == 1}
else if (age > 10 & age <= 20) {group == 2}
else {group == 3}
if you put your statement on one line it works (at least it does not
give you syntax error) but the result is hardly what you really expect
age<-sample(seq(10,50,10), 20, replace=T)
if (age <=10) {group <- 1} else if (age > 10 & age <= 20) {group <- 2}
else {group <- 3}
if (age <=10) {group == 1} else if (age > 10 & age <= 20) {group == 2}
else {group == 3}
Maybe you want something like
group<-as.numeric(cut(age,c(0,10,20,100)))
but it is only guess
HTH
Petr
Syntax error
Or
if (age <=10) {group == 1}
else (age > 10 & age <= 20) {group == 2}
else {group == 3}
Syntax error
I know that is possible to find the solution by ifelse command or even
recode command, but I??d like to use this way, because I can add
another variable as a new condition and I believe to expand the
possibilites.
Thanks,
Mauricio
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