Rearrange rows in data frame

Question

I have a data frame in R which looks like this with two columns:

ID     phone_number
Mark     866458
Paul     986564
Jack     987543
Mary     523422

I would like to have this kind of output where I only have one single column

Mark
866458
Paul
986564
Jack
987543
Mary
523422

Anybody knows which R code could I use to obtain the output?

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Data for reproducibility:

structure(list(ID = c("Mark", "Paul", "Jack", "Mary"), phone_number = c(866458, 
                                                                        986564, 987543, 523422)), row.names = c(NA, -4L), class = c("tbl_df", "data.frame"))

Answer 1

We can transpose the dataframe and then create one vector of values

data.frame(new_col = c(t(df)))

#  new_col
#1    Mark
#2  866458
#3    Paul
#4  986564
#5    Jack
#6  987543
#7    Mary
#8  523422

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Another base R option using mapply

data.frame(new_col = c(mapply(c, df$ID, df$phone_number)))