Case and/or Variable Selection (Subsets of Data)

You may select cases (or variables) from a data set for further analysis. Actually, there is a huge number of ways this can be accomplished

The subset command

The easiest way of case selection is probably subset. Here is an example:

sub1.xdata <- subset(xdata, inc > 1000)

This assigns a subset of xdata to the new object sub1.xdata. This subset consist of all cases that have values larger than 1000 in variable 'inc'.

The subset command can be used for variable selection as well, as in:

sub1.xdata <- subset(xdata, inc > 1000, select=c(var1,var2))

The "[]" operator

The same effect as demonstrated above with the help of subset can be achieved like this:

sub2.xdata <- xdata[xdata$inc >1000]