How to rbind the data with different number of column in R?

Question

I would like to bind the 2 different length of data frame with some constraint but I'm not sure how to do that. After I run the code, it said that "the numbers of columns of arguments do not match".

I would like to bind the two different data frame based on their column names. Based on the sample data below, I would like to have a combined data frame such that the row names of dtf2 become the first column while the first column for dtf1 is still remain as the same. I attached diagram below for the expected output that I want.

The code below is my sample data

a <- c(1,2,3,4,5,6,6,7,7)
b <- c(11,3,6.5,7,8,9,3,2,5)
dtf1 <- as.data.frame(rbind(a,b))
colnames(dtf1) <- c("aa","bb","cc","dd","ee","ff","gg","hh","ii")

c <- c(1,2,3,4,5,6,7,8)
d <-c(10,9,8,7,6,5,4,3)
dtf2 <- as.data.frame(rbind(c,d))
colnames(dtf2) <- c("bb","cc","dd","ee","ff","gg","hh","ii")

rbind(dtf1,dtf2)

This diagram is the expected output that I desire:

Answer 1

You could first cbind the rownames in dtf2 and rbind it with dtf1.

rbind(dtf1, cbind(aa = rownames(dtf2), dtf2))

#  aa bb  cc dd ee ff gg hh ii
#a  1  2 3.0  4  5  6  6  7  7
#b 11  3 6.5  7  8  9  3  2  5
#c  c  1 2.0  3  4  5  6  7  8
#d  d 10 9.0  8  7  6  5  4  3

---

Using dplyr, it doesn't directly coerce the column to character so you need to explicitly mention it.

library(dplyr)
bind_rows(dtf1 %>% mutate(aa = as.character(aa)), 
          bind_cols(aa = rownames(dtf2), dtf2))