combine unequal dataframes with dplyr::bind_rows

library(dplyr)

## use a vector for the files and the dataframes, where we leave a column in some of them

fn <- c("test_1.csv", "test_2.csv", "test_3.csv")

dl <- c(
  mtcars %>% select(-gear), 
  mtcars %>% select(-disp), 
  mtcars %>% select(-wt) 
)

# write all the files
for(i in 1:3){
  dl[[i]] %>% write.csv(fn[[i]])
}

# use Map to read all files in one line
sets <- Map(read.csv, fn)

# or equivalently
sets <- list(
  read.csv(fn[[1]]),
  read.csv(fn[[2]]),
  read.csv(fn[[3]])
)

# then use Reduce to combine the sets
# they have different columns, 
# but noone is complaining, only someone is silently inserting NA's
full.set <- Reduce(bind_rows, sets)

# or equivalently
full.set <- sets[[1]] %>% bind_rows(sets[[2]]) %>% bind_rows(sets[[3]])