Long to wide data with tidyR?

Question

I have data that looks something like this

df = data.frame(name=c("A","A","B","B"),
                group=c("g1","g2","g1","g2"),
                V1=c(10,40,20,30),
                V2=c(6,3,1,7))

I want to reshape it to look like this:

df = data.frame(name=c("A", "B"),               
                V1.g1=c(10,20),
                V1.g2=c(40,30),
                V2.g1=c(6,1),
                V2.g2=c(3,7))

Is it possible to do it with tidyR?

I can do it with reshape

reshape(df, idvar='name', timevar='group', direction='wide')

but is always good to learn something new.

Answer 1

The reshape code is compact as it works for multiple value columns. Using the same in tidyr, may need a couple of steps. Convert the 'wide' format to 'long' using gather so that there will be a single 'Val' column, unite the 'Var' (from previous step) and 'group' columns to create a single 'VarG' column, and then use spread to reconvert the 'long' to 'wide' format.

library(tidyr)
gather(df, Var, Val, V1:V2) %>% 
                unite(VarG, Var, group) %>% 
                spread(VarG, Val)
#    name V1_g1 V1_g2 V2_g1 V2_g2
#1    A    10    40     6     3
#2    B    20    30     1     7