Create a data.frame with m columns and 2 rows

Question

I would like to create a data.frame in R with m (a variable) number of columns (for example 30), and 2 rows and fill all the values in the data.frame initially with 0\'s. It see

Answer 1

For completeness:

Along the lines of Chase's answer, I usually use as.data.frame to coerce the matrix to a data.frame:

m <- as.data.frame(matrix(0, ncol = 30, nrow = 2))

EDIT: speed test data.frame vs. as.data.frame

system.time(replicate(10000, data.frame(matrix(0, ncol = 30, nrow = 2))))
   user  system elapsed 
  8.005   0.108   8.165 

system.time(replicate(10000, as.data.frame(matrix(0, ncol = 30, nrow = 2))))
   user  system elapsed 
  3.759   0.048   3.802 

Yes, it appears to be faster (by about 2 times).

Answer 2

Does m really need to be a data.frame() or will a matrix() suffice?

m <- matrix(0, ncol = 30, nrow = 2)

You can wrap a data.frame() around that if you need to:

m <- data.frame(m)

or all in one line: m <- data.frame(matrix(0, ncol = 30, nrow = 2))