[R] to modify a dataframe

[Bert Gunter]

1. Thank you for the clear reproducible example. This made it easy to
see what you wanted and provide an answer. Hopefully a correct one!

2. Many ways to do this. Here's one, but others may be better.

Step1: First greate a grouping factor for Nom to group the separate
row labels into the logical groups you have specified:

grp <- factor(substring(df1$Nom,1,1))

Note that you may need to use regular expressions or some other method
to do this if your naming system is more complex than you have shown.

Step 2: Create your new structure:

df2 <- df1
df2[,-1]<-lapply(df1[-1],function(x)ave(x,grp,FUN=max))

HTH.

Cheers,
Bert

Bert Gunter
Genentech Nonclinical Biostatistics
(650) 467-7374

"Data is not information. Information is not knowledge. And knowledge
is certainly not wisdom."
H. Gilbert Welch




On Wed, Jan 1, 2014 at 8:55 AM, Arnaud Michel <michel.arnaud at cirad.fr> wrote:
> Dear All,
>
> From the dataframe df1
>
> df1 <-
> structure(list(Nom = structure(1:9, .Label = c("A1", "A2", "A3",
> "B1", "B2", "C1", "C2", "C3", "C4"), class = "factor"), Pays1 = c(1,
> 1, 0, 0, 1, 0, 0, 0, 0), Pays2 = c(0, 0, 0, 1, 1, 0, 1, 0, 1),
>     Pays3 = c(0, 0, 0, 0, 1, 0, 0, 0, 0), Pays4 = c(1, 0, 0,
>     0, 0, 0, 1, 0, 1), Pays5 = c(1, 1, 0, 0, 0, 0, 0, 0, 0)), .Names =
> c("Nom",
> "Pays1", "Pays2", "Pays3", "Pays4", "Pays5"), row.names = c(1L,
> 3L, 4L, 2L, 5L, 6L, 7L, 8L, 9L), class = "data.frame")
>
>
> I look for a way to build the new dataframe df2
>  df2 <-
> structure(list(Nom = structure(1:9, .Label = c("A1", "A2", "A3",
> "B1", "B2", "C1", "C2", "C3", "C4"), class = "factor"), Pays1 = c(1,
> 1, 1, 1, 1, 0, 0, 0, 0), Pays2 = c(0, 0, 0, 1, 1, 1, 1, 1, 1),
>     Pays3 = c(0, 0, 0, 1, 1, 0, 0, 0, 0), Pays4 = c(1, 1, 1,
>     0, 0, 1, 1, 1, 1), Pays5 = c(1, 1, 1, 0, 0, 0, 0, 0, 0)), .Names =
> c("Nom",
> "Pays1", "Pays2", "Pays3", "Pays4", "Pays5"), row.names = c(NA,
> -9L), class = "data.frame")
>
> The purpose is to transform df1 it df2 by giving for every group of lines A,
> B and C the value 1 if there is at least a value equal to 1 or a value 0 if
> there is no value equal to 1
>
> Thanks for your helps
>
> --
> Michel ARNAUD
> Chargé de mission auprès du DRH
> DGDRD-Drh - TA 174/04
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>
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