Hi all, I created a data frame with three factors, plus the response that looks like this: x1 x2 x3 y a 1 1 0.3 a 2 1 0.1 b 1 1 0.4 c 4 3 0.1 ... I would like to analise the effect of two of them, keeping the third fixed (I already know the effect of the last). The reason why I don't create several data frames for each value of the thirs factor is simply convenience (I'd like to be able to decide which factor I want to rule out) for example I'd like to write something like boxplot(y ~ x1 + x2, x3 == 1) which of course doesn't work, otherwise I wouldn't write :-) Is this possible and how? Thank you Giampiero
how to fix a factor
4 messages · Giampiero Salvi, Chuck Cleland, Vaclav Petricek +1 more
Giampiero Salvi wrote:
I created a data frame with three factors, plus the response that looks like this: x1 x2 x3 y a 1 1 0.3 a 2 1 0.1 b 1 1 0.4 c 4 3 0.1 ... I would like to analise the effect of two of them, keeping the third fixed (I already know the effect of the last). The reason why I don't create several data frames for each value of the thirs factor is simply convenience (I'd like to be able to decide which factor I want to rule out)
boxplot(y ~ x1 + x2, data = mydata[mydata$x3==1,])
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On Fri, 19 Mar 2004, Giampiero Salvi wrote:
Hi all, I created a data frame with three factors, plus the response that looks like this: x1 x2 x3 y a 1 1 0.3 a 2 1 0.1 b 1 1 0.4 c 4 3 0.1 ... I would like to analise the effect of two of them, keeping the third fixed (I already know the effect of the last). The reason why I don't create several data frames for each value of the thirs factor is simply convenience (I'd like to be able to decide which factor I want to rule out) for example I'd like to write something like boxplot(y ~ x1 + x2, x3 == 1) which of course doesn't work, otherwise I wouldn't write :-) Is this possible and how?
?boxplot The subset parameter of boxplot might be what you are looking for. Vaclav
Giampiero, It's certainly possible. Many commands allow the "subset" option, which permits the analysis of only a portion of a dataframe, although boxplot does not. Also, you could preface your analysis with a logical condition, like my sample <- x3 == 1 boxplot(y[my sample] ~ x1[my sample] + x2[my sample]) You can wrap the preceding code in a for loop to apply it to each level of the factor. Frank Harrell's useful mapply() will allow you to vectorize over more than one argument. Look for it in the package Hmisc on CRAN. Andrew
On Friday 19 March 2004 08:31, Giampiero Salvi wrote:
Hi all, I created a data frame with three factors, plus the response that looks like this: x1 x2 x3 y a 1 1 0.3 a 2 1 0.1 b 1 1 0.4 c 4 3 0.1 ... I would like to analise the effect of two of them, keeping the third fixed (I already know the effect of the last). The reason why I don't create several data frames for each value of the thirs factor is simply convenience (I'd like to be able to decide which factor I want to rule out) for example I'd like to write something like boxplot(y ~ x1 + x2, x3 == 1) which of course doesn't work, otherwise I wouldn't write :-) Is this possible and how? Thank you Giampiero
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