R-如何通过更改主要唯一行变量将宽数据集重新格式化为宽数据集

Question

Sorry if this has been asked already and if the title is very confusing. I did look and only found questions on reformating where the values of one of the columns were used as column headings in the output dataset.

My dataset is organized so the Filter is the unique value for each row. I want to change it so the id of the individual within each sampling season is unique for each row since individuals had multiple filters. Basically, I want to reformat Table 1 so it looks like Table 2.

Table 1
       id season FilterI 
    1:  1      1       A 
    2:  1      1       B 
    3:  2      1       C 
    4:  2      1       D 
    5:  1      2       E 
    6:  1      2       F 

Table 2
       id season FilterI1 FilterI2
    1:  1      1       A        B
    2:  1      2       E        F
    3:  2      1       C        D

Reshape does not seem to work because none of the columns in the first dataset contain the column headings for the second dataset.

Answer 1

Using dcast with rowid , change from 'long' to 'wide' (assuming the example data is data.table )

library(data.table)
dcast(Table1, id + season ~ paste0("FilterI", rowid(id)), value.var = "FilterI")
#     id season FilterI1 FilterI2
#1:  1      1        A        B
#2:  1      2        E        F
#3:  2      1        C        D