Find means of columns in selected rows of biological sample data

I am doing an MSc and have been given a project task which I can't get my head around. The csv dataset which has 12 columns and 25 rows including the headers. The samples are divided into 4 sets, AIR1-AIR6, DCA1-DCA6 = controls and AIR7-AIR12, DCA7-DCA12.

We have been asked to calculate descriptive stats (mean, median, sd) for the the controls (AIR1-AIR6, DCA1-DCA6) and the data AIR7-AIR12, DCA7-DCA12 to see if there are any differences.

My question is how can I do this in the most simple way in rstudio?

I'll use the built-in mtcars as an example. We'll take cyl as the treatment variable.

st(mtcars, group = "cyl", add.median = TRUE)

What, that's it? Well, not really. In the R spirit of lazy evaluation I weighed doing this manually versus finding a package for what is really a very common task and learning how to use it. It started with a search of summary statistics on rseek.

I could have done this in base{} simply by

apply(mtcars[which(mtcars$cyl == 4),-2],2,sd)
#>        mpg       disp         hp       drat         wt       qsec         vs 
#>  4.5098277 26.8715937 20.9345300  0.3654711  0.5695637  1.6824452  0.3015113 
#>         am       gear       carb 
#>  0.4670994  0.5393599  0.5222330

for the 4 cyl treatment sd.

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