How add a row of 0 to a dataframe

Question

I have this dataframe in R

mat <-structure(list(a = c(2, 5, 90, 77, 56), b = c(45, 78, 98, 55, 
63), c = c(77, 85, 3, 22, 4), d = c(52, 68, 4, 25, 79), e = c(14, 
73, 91, 87, 94)), class = "data.frame", row.names = c(NA, -5L
))

and I want add a row of "0" as first row of mat. The output that I need is

   a  b  c  d  e
1  0  0  0  0  0
2  2 45 77 52 14
3  5 78 85 68 73
4 90 98  3  4 91
5 77 55 22 25 87
6 56 63  4 79 94

How can I do? Thx

Answer 1

We can use rbind

mat <- rbind(0, mat)

-output

mat
   a  b  c  d  e
1  0  0  0  0  0
2  2 45 77 52 14
3  5 78 85 68 73
4 90 98  3  4 91
5 77 55 22 25 87
6 56 63  4 79 94

Answer 2

Here is another option using tidyverse, where we iterate through each column to add a 0 to the first position, then bind back together as a dataframe.

library(tidyverse)

map_df(mat, ~ c(0, .x))

Output

      a     b     c     d     e
  <dbl> <dbl> <dbl> <dbl> <dbl>
1     0     0     0     0     0
2     2    45    77    52    14
3     5    78    85    68    73
4    90    98     3     4    91
5    77    55    22    25    87
6    56    63     4    79    94

Or another option would be to keep only the first row of the dataframe, then change all the values to 0, then use bind_rows to add to mat.

bind_rows(mutate(mat[1, ], across(everything(), ~ 0)), mat)