How can a add a row to a data frame in R?

In R, how do you add a new row to a data frame once the data frame has already been initialized?

So far I have this:

df <- data.frame("hi", "bye")
names(df) <- c("hello", "goodbye")

#I am trying to add "hola" and "ciao" as a new row
de <- data.frame("hola", "ciao")

merge(df, de) # Adds to the same row as new columns

# Unfortunately, I couldn't find an rbind() solution that wouldn't give me an error

Any help would be appreciated

Like @Khashaa and @Richard Scriven point out in comments, you have to set consistent column names for all the data frames you want to append.

Hence, you need to explicitly declare the columns names for the second data frame, de, then use rbind(). You only set column names for the first data frame, df:

df<-data.frame("hi","bye")
names(df)<-c("hello","goodbye")

de<-data.frame("hola","ciao")
names(de)<-c("hello","goodbye")

newdf <- rbind(df, de)

Let's make it simple:

df[nrow(df) + 1,] = c("v1","v2")

There's now add_row() from the tibble or tidyverse packages.

library(tidyverse)
df %>% add_row(hello = "hola", goodbye = "ciao")

Unspecified columns get an NA.

Or, as inspired by @MatheusAraujo:

df[nrow(df) + 1,] = list("v1","v2")

This would allow for mixed data types.

I like list instead of c because it handles mixed data types better. Adding an additional column to the original poster's question:

#Create an empty data frame
df <- data.frame(hello=character(), goodbye=character(), volume=double())
de <- list(hello="hi", goodbye="bye", volume=3.0)
df = rbind(df,de, stringsAsFactors=FALSE)
de <- list(hello="hola", goodbye="ciao", volume=13.1)
df = rbind(df,de, stringsAsFactors=FALSE)

Note that some additional control is required if the string/factor conversion is important.

Or using the original variables with the solution from MatheusAraujo/Ytsen de Boer:

df[nrow(df) + 1,] = list(hello="hallo",goodbye="auf wiedersehen", volume=20.2)

Note that this solution doesn't work well with the strings unless there is existing data in the dataframe.