Question

I have a text file which is a 1000 Row * 40001 Column table.

The first Column of the file is a string and the other columns are some float numbers, such as this:

A 2 3 4.54 .... 11.23
B 6 6 7 ....    23.45

I want to read this file into a matice but read.table seems not very efficient for large files, so I think scan may be the right tool for that?

However, scan can only accept numbers as input by default. If I want non-number as input, I need to change the what parameter. But as there’re 40000+ columns, I can’t assign the type of input for each input..

Does anyone know how to use it? Thanks!

Answer 1

You could use the what argument and specify a list of types (like colClasses).

Lines <-
"A 2 3 4.54 11.23
B 6 6 7 23.45"
Data <- (scan(textConnection(Lines), what=c(list(NULL), rep(0,4))))
(Data <- do.call(cbind, Data))
#      [,1] [,2] [,3]  [,4]
# [1,]    2    3 4.54 11.23
# [2,]    6    6 7.00 23.45