Is there a way to apply a function, say cor(), to each combination of some
number of variables, and this, without using loops?
For example, I have day, hour, var1 and var2. How could I compute
cor(var1,var2) for each day*hour combination and obtain a matrix with day,
hour and the cor value for
you could use something like
by(data, list(data1$day, data1$hour), function(x) cor(x[,var1], x[,
var2]))
This will return a list and then you can unlist and turn to matrix
HTH
Is there a way to apply a function, say cor(), to each combination of some
number of variables, and this, without
