长到宽格式，字符值在r中

Question

I have a long data frame as below:

   Date        Time         Type
    1            1            A
    1            2            B
    1            3            C
    2            2            C
    2            3            D 
    2            5            A
    2            7            E

I want to change it to a wide format like the following:

   Date      Time1    Time2    Time3   Time4    Time5    Time6   Time7
     1         A        B        C
     2                  C        D                A                E

I used the following code but it only gives me 0 and 1 values instead of 'Type' values:

   df_index = ddply(df, .(Date), mutate, index = paste0('Time', 1:length(Date)))
   df2 = dcast(df_index, Date ~ index, value.var = 'Type')   

Could you please help me here?

Answer 1

You can use tidyr (part of the fantastic tidyverse you should look into) to do this fairly easily.

install.packages('tidyr')
install.packages('dplyr')

library(tidyr)
library(dplyr)

all_times <- data.frame(Time = c(1:6))
df <- data.frame(Date = c(1, 1, 1, 2, 2, 2, 2), Time = c(1, 2, 3, 2, 3, 5, 7),Type = c('A', 'B', 'C', 'C', 'D', 'A', 'E'))

spread_df <- df %>% right_join(all_times) %>% spread(Time, Type, sep = '.') %>% filter(!is.na(Date))

Edited based on PoGibas's comment