[R] extract data from square cracket

[Marc Girondot]

Le 17/05/12 03:37, Min Wang a écrit :
> Dear Sir or Madam,
>
> I have a question like this. I want to extract the following data from the
> square bracket:
>
>     1		band            band            [0.86]
>     2		band            band            [0.93]
>     3		noband          noband          [0.95]
>     4		noband          noband          [0.91]
>     5		noband          noband          [0.89]
>     6		noband          noband          [0.84]
>     7		noband          noband          [0.89]
>     8		band            noband          [0.80]
>     9		band            band            [0.75]
>    10		band            band            [0.93]
>
> For the 4th column, I want to get the numerical values inside the bracket.
> How can I use R code to implement this? Thanks.
>
>
Many possibilities. For exemple:
 > a <- '[0.84]'
 > gsub("[^[:digit:].]", "", a)
[1] "0.84"

Look at
?gsub

To reproduce your specific example:
d <- data.frame(col1=c(rep("band", 2), rep("noband", 5), rep("band", 3)))
d<- data.frame(cbind(d, col2=c(rep("band", 2), rep("noband", 6), 
rep("band", 2))))
d<- data.frame(cbind(d, col3=c("[0.86]", "[0.93]", "[0.95]", "[0.91]", 
"[0.89]", "[0.84]", "[0.89]", "[0.80]", "[0.75]", "[0.93]")))
as.numeric(gsub("[^[:digit:].]", "", d[,"col3"]))

Then you get:
  [1] 0.86 0.93 0.95 0.91 0.89 0.84 0.89 0.80 0.75 0.93

Sincerely,
Marc

-- 
__________________________________________________________
Marc Girondot, Pr

Laboratoire Ecologie, Systématique et Evolution
Equipe de Conservation des Populations et des Communautés
CNRS, AgroParisTech et Université Paris-Sud 11 , UMR 8079
Bâtiment 362
91405 Orsay Cedex, France

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