r - Merge data with same key to one row -

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• how reshape data long wide format? 7 answers

i have data frame several data this

key     b c 1       1 2 3 1       4 6 8 1       3 2 1 

i need merge these data same key 1 row this

key      a1 b1 c1 a2 b2 c2 a3 b3 c3 1        1  2  3  4  6  8  3  2  1  

is there easy way result need.

if single group of 'key', 1 option use base r. transpose (t) dataset except first column (df[-1]), concatenate vector, convert data.frme , cbind first element of first column.

res <- cbind(df1[1,1], as.data.frame.list(c(t(df1[-1])))) names(res) <- c(names(df1)[1] ,make.unique(rep(names(df1)[-1],3))) res #  key b c a.1 b.1 c.1 a.2 b.2 c.2 #1   1 1 2 3   4   6   8   3   2   1 

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or use data.table i.e. development version v1.9.7 if there many 'key' elements

library(data.table) dcast(setdt(df1), key~rowid(key), value.var = c("a", "b", "c"),sep="") #   key a1 a2 a3 b1 b2 b3 c1 c2 c3 #1:   1  1  4  3  2  6  2  3  8  1 

if have data.table version < v1.9.7, need create sequence column grouped 'key'.

dcast(setdt(df1)[, rn := 1:.n , key], key ~rn, value.var = c("a", "b", "c"),sep="") #   key a1 a2 a3 b1 b2 b3 c1 c2 c3 #1:   1  1  4  3  2  6  2  3  8  1