[R] Looping through different groups of variables in models

Jim Lemon drjimlemon at gmail.com
Thu Sep 1 00:39:07 CEST 2016

Hi Kai,
Perhaps something like this:

for(timeindx in levels(kmdf$time)) {
 for(condindx in levels(kmdf$condition)) {
  subdat<-kmdf[kmdf$time == timeindx & kmdf$condition == condindx,]

Getting elegant output is another matter. Have a look at packages
meant to produce fancier R output.


On Thu, Sep 1, 2016 at 7:58 AM, Kai Mx <govokai at gmail.com> wrote:
> Hi all,
> I am having trouble wrapping my head around a probably simple issue:
> After using the reshape package, I have a melted dataframe with the columns
> group (factor), time (int), condition (factor), value(int).
> These are experimental data. The data were obtained from different
> treatment groups (group) under different conditions at different time
> points.
> I would now like to perform ANOVA, boxplots and calculate means to compare
> groups for all combinations of conditions and time points with something
> like
> fit <- lm(value~group, data=[subset of data with combination of
> condition/timepoint])
> summary (fit)
> p <- ggplot([subset of data with combination of condition/timepoint],
> aes(x= group, y=value)) + geom_boxplot ()
> print (p)
> tapply ([subset of data with combination of condition/timepoint]$value,
> subset of data with combination of condition/timepoint]$group, mean)
> How can I loop through these combinations and output the data in an elegant
> way?
> Thanks so much!
> Best,
> Kai
>         [[alternative HTML version deleted]]
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