How to reshape tabular data to one row per group

Question

I am an R (and coding novice) and I am looking for a way to reconfigure Table A show below into Table B.

Table A:

type   x1  x2  x3  
A      4   6            


        

Answer 1

a <- data.frame(type=c("A", "A","A", "B", "B"), x1 = c(4,7,9,1,2),x2=c(6,4,6,3,7),
               x3 = c(9,1,2,8,9))

library(dplyr)
tmp <-
a %>% 
  group_by(type) %>%
  summarise(no_rows = length(type))

for(i in unique(a$type)){
  n <- max(tmp$no_rows) - nrow(a[a$type == i,])
  nn <- nrow(a)
  if(n > 0){
    for(ii in 1:n){
      a[nn+ii,] <- c(i,NA,NA,NA)
    }    
  }

}

a <- a[order(a$type),]
a$timevar <- seq(1:max(tmp$no_rows) )

b<-reshape(a,timevar="timevar",idvar="type",direction="wide",drop = F)
b

  type x1.1 x2.1 x3.1 x1.2 x2.2 x3.2 x1.3 x2.3 x3.3
1    A    4    6    9    7    4    1    9    6    2
4    B    1    3    8    2    7    9