How to use dcast and aggregate function in R for a list of data?

General
12

Is this what you mean by adding a total row?

library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union
DF1 <- data.frame(PROVINCE = rep(c("A", "B", "C"), 4),
                  ETHNICITY = rep(c("Y", "Z"), 6),
                  WEIGHT = runif(12, min = 40, max = 60))

DF2 <- data.frame(PROVINCE = rep(c("A", "B", "C"), 4),
                  ETHNICITY = rep(c("Y", "Z"), 6),
                  WEIGHT = runif(12, min = 40, max = 60))

MyList <- list(DF1, DF2)
MyFunc <- function(DatFrame) {
  tmp <- reshape2::dcast(data = DatFrame, formula = PROVINCE ~ ETHNICITY, 
                  value.var = "WEIGHT", fun.aggregate = sum)
  SUMS <- tmp %>% summarize(across(.col=where(is.numeric), sum))
  SummaryRow <- bind_cols(data.frame(PROVINCE="TOTAL"),SUMS)
  bind_rows(tmp, SummaryRow)
}
DCAST_out <- lapply(X = MyList, FUN = MyFunc)
DCAST_out
#> [[1]]
#>   PROVINCE         Y         Z
#> 1        A 108.14376 109.16078
#> 2        B  97.54265 114.88119
#> 3        C  91.41058  98.30363
#> 4    TOTAL 297.09699 322.34560
#> 
#> [[2]]
#>   PROVINCE         Y         Z
#> 1        A 100.91991  94.33169
#> 2        B 106.15745 114.00632
#> 3        C  98.59599 103.73327
#> 4    TOTAL 305.67335 312.07127

Created on 2020-12-13 by the reprex package (v0.3.0)