How to avoid: read.table truncates numeric values beginning with 0

I want to import a table (.txt file) in R with read.table(). One column in my table is an ID with nine numerals - some ids begin with a 0, other with 1 or 2.

R truncates the first 0 (012345678 becomes 12345678) which leads to problems when using this ID to merge another table.

Can someone give me a hint how to solve the problem?

Solution 1:

As said in Ben's answer, colClasses is the easier way to do it. Here is an example:

read.table(text = 'col1 col2
           0012 0001245',
           head=T,
           colClasses=c('character','numeric'))

  col1 col2
1 0012 1245      ## col1 keep 00 but not col2

Solution 2:

A reproducible example would be nice, but: use the colClasses argument to read.table() to specify that you want this column to be read as a character variable, not numeric. Or make them back into character variables after reading them in, using sprintf to pad the numbers with leading zeros. (The former is probably easier.)