[R] list substring

[Wacek Kusnierczyk]

calpeda wrote:
> thank you,
> but I m importing data from a txt file and I have a matrix of n*1
> The function str seems to work only from 1*n
>
>   

you see, it would help if you provided more details from the start.  you
may still need to do it;  it seems that both solutions you were given
(mine and the substr one) work for both n*1 and 1*n matrices:

    # 5*1
    (strings = matrix(as.character(sample(10^6, 5)), ncol=1))
   
    substr(strings, 1, 4)
    substr(t(strings), 1, 4)

with a fixed pattern of four digits from the beginning of the string,
the substr solution is better -- simpler and a few times faster.

vQ