[R] Odp: arguments must have same length

[Petr PIKAL]

Hi


> 
> > score<-read.csv("http://users.stat.umn.edu/~chen2285/hw/ACT.csv")


> score<-read.csv("http://users.stat.umn.edu/~chen2285/hw/ACT.csv")
Error in file(file, "rt") : cannot open the connection
In addition: Warning message:
In file(file, "rt") : unable to connect to 'users.stat.umn.edu' on port 
80.
>

Unable to read data.

> 
> > interaction.plot(sex,rep(1,861),score,fun=mean,legend=F,main="profile 
of
> > sex")
> Error: tapply(response, list(x.factor, trace.factor), fun) : 
>   arguments must have same length

However you are not telling us whole story. score shall be data frame and 
length(data.frame) results in number of columns.

>From help page

x.factor a factor whose levels will form the x axis.
trace.factor another factor whose levels will form the traces.
response a numeric variable giving the response
 
your second variable to interaction plot is numeric - shall be factor
your third variable is probably data frame, shall be numeric.

It is advisable to give to functions values they expect. Some functions 
can crunch unexpected data but the results can be misleading if not wrong.

Regards
Petr

> 
> > length(sex)
> [1] 861
> > length(type)
> [1] 861
> > length(score)
> [1] 3
> 
> How can I alter the length of the variable score here to make this 
function
> work?
> or any other way to perform interaction plot? 
> 
> 
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