rbind data frames only for same columns

问题

I have 24 data frames that I need to combine. 20 data frames have the same 238 columns, instead 4 data frames have 256 columns. Moreover, the 4 data frames with 256 columns have a different order of columns compared to the other 20 data frames.

E.g. 'answer', 'condition', 'msg_time', 'fix', etc. (20 data frames)

E.g. 'acc_value', 'nitem', 'fix', 'button_press_0', 'rotation', 'previous_fix', 'accuracy', 'answer','file', 'condition', etc. (4 data frames)

I would like to rbind only those columns that are the same in all 24 data frames. Any suggestion would be really appreciated. Thank you.

回答1:

It's not the most elegant solution, but it works.

df <- data.frame()            # empty data.frame
base_names <- names(a)        # base_names will reflect any data.frame that has 238 observations
list_df <- list(a, b, c)      # list of all your data frames

for(item in list_df){         # create loop

  items <- item[, base_names] # only select columns that match the 238 columns
  df <- rbind(df, items)      # append those to the data.frame

}

df                            # all data.frames rbinded

---

If you want to avoid loops, you can also use lapply

library(plyr)
library(dplyr) 

df <- data.frame()
base_names <- names(a)
list_df <- list(a, b, c)  

lapply(list_df,
       function(x){

         x_cols <- x[, base_names]
         df <- rbind(df, x_cols)

       }) %>% plyr::ldply(rbind)

来源：https://stackoverflow.com/questions/33123494/rbind-data-frames-only-for-same-columns