[R] grep

[Marc Schwartz]

On Fri, 2004-03-12 at 11:08, Ernesto Jardim wrote:
> Hi,
> 
> I want to use the first digit of the elements of a vector.
> 
> I've tried grep but didn't work.
> 
> Any help is welcome.
> 
> Thanks
> 
> EJ
> 
> > grep("^[0-9]",as.character(runif(100,0,2)))
>   [1]   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16 
> 17  18
>  [19]  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34 
> 35  36
>  [37]  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52 
> 53  54
>  [55]  55  56  57  58  59  60  61  62  63  64  65  66  67  68  69  70 
> 71  72
>  [73]  73  74  75  76  77  78  79  80  81  82  83  84  85  86  87  88 
> 89  90
>  [91]  91  92  93  94  95  96  97  98  99 100


How about ?substr

> substr(as.character(runif(100, 0, 2)), 1, 1)
  [1] "0" "1" "0" "1" "0" "0" "0" "0" "0" "1" "1" "1" "0" "0" "1" "0"
 [17] "1" "0" "1" "1" "1" "1" "0" "1" "0" "1" "0" "1" "1" "0" "1" "0"
 [33] "1" "0" "1" "0" "0" "1" "0" "0" "0" "0" "0" "0" "0" "0" "1" "0"
 [49] "1" "1" "0" "0" "0" "1" "1" "1" "0" "1" "0" "1" "0" "1" "1" "1"
 [65] "1" "0" "1" "1" "1" "1" "1" "0" "1" "1" "0" "1" "0" "1" "0" "0"
 [81] "1" "1" "0" "0" "1" "1" "0" "1" "0" "0" "0" "0" "0" "0" "0" "1"
 [97] "0" "0" "0" "1"

or

> substr(as.character(1:100), 1, 1)
  [1] "1" "2" "3" "4" "5" "6" "7" "8" "9" "1" "1" "1" "1" "1" "1" "1"
 [17] "1" "1" "1" "2" "2" "2" "2" "2" "2" "2" "2" "2" "2" "3" "3" "3"
 [33] "3" "3" "3" "3" "3" "3" "3" "4" "4" "4" "4" "4" "4" "4" "4" "4"
 [49] "4" "5" "5" "5" "5" "5" "5" "5" "5" "5" "5" "6" "6" "6" "6" "6"
 [65] "6" "6" "6" "6" "6" "7" "7" "7" "7" "7" "7" "7" "7" "7" "7" "8"
 [81] "8" "8" "8" "8" "8" "8" "8" "8" "8" "9" "9" "9" "9" "9" "9" "9"
 [97] "9" "9" "9" "1"


HTH,

Marc Schwartz