data.table - Create a table for N, Min/Max, SD, Mean, and Median in R

Question

I'm very new to R, so please bear with me on this basic question. I have a dataset, DATA, that I created using the data.table package. I created 200 random numbers between 0 and 1, then did that 10000 times, finally creating a data table for with descriptive statistics for each iteration. My code for it looked like this:

rndm<-runif(200, min=0, max=1)
reps <- data.table(x=runif(200*10000),iter=rep(1:200,each=10000))
DATA <- reps[,list(mean=mean(rndm),median=median(rndm),sd=sd(rndm),min=min(rndm),
max=max(rndm)),by=iter]

The data looks something like this:

    Mean    Median     SD    Min    Max
1   0.521    0.499   0.287  0.010  0.998
2   0.511    0.502   0.290  0.009  0.996
.    ...     ... 

etc.

What I want to do is create a table that finds N, mean, median, standard deviation, minimum, and maximum of the accumulated sample means (not of each column like above). I need the output to look something like this:

   N     Mean   Median    SD    Min    Max
 10000  .502     .499    .280  .002   .999

How can I accomplish this?

Answer 1

You could also define a function. This approach allows you to make the same table for a different variable.

summaryfun <- function(x)list(N=length(x),Mean=mean(x),Median=median(x),SD=sd(x),Min=min(x),Max=max(x))
DATA[,summaryfun(mean)]