Collapse large list into dataframe but preserve number of list in R-CodePudding

I have a large list in R. It comprises 20 different dataframes, each with two variables (columns). These variables are the same for each of the dataframes within the large list. I am collapsing the dataframe with the rbindlist function from the data.table package. This works successfully, yielding a single dataframe with all of the observations of the 2 variables. However, I would like to add a third variable for each list (and for the ultimate dataframe) that contains the number of the list that each unit/observation is contained in.

For example: Unit 1 is (1, 235) and is located in the first list. Unit 1 in the new dataframe should now be (1,235,1) in the new dataframe. Unit 2 is (2, 248) and is located in the first list. Its three columns' values should now be (2,248,1) in the new dataframe. Unit 3 is (3,78), but it is located in the second list. So its three columns' values should now be (3,78,2).

Is it possible to preserve the number/placement of the individual unit within the large list when collapsing it into one dataframe?

CodePudding user response：

Are you trying to do this?

library(dplyr)

df1 <- data.frame(v1 = 1:5, v2 = sample(50:60, 5))
df2 <- data.frame(v1 = 6:10, v2 = sample(50:60, 5))
df3 <- data.frame(v1 = 11:15, v2 = sample(50:60, 5))

l <- list(df1, df2, df3)

bind_rows(l, .id = "id")

#>    id v1 v2
#> 1   1  1 58
#> 2   1  2 54
#> 3   1  3 56
#> 4   1  4 57
#> 5   1  5 60
#> 6   2  6 57
#> 7   2  7 56
#> 8   2  8 55
#> 9   2  9 60
#> 10  2 10 52
#> 11  3 11 59
#> 12  3 12 51
#> 13  3 13 52
#> 14  3 14 55
#> 15  3 15 53

^{Created on 2022-07-08 by the reprex package (v2.0.1)}

I don't know about data.table much, that's why used dplyr instead