How to add new rows to text file with missing data?

I have a txt file containing 4 tab delineated columns that are missing rows, like;

1, x, y, z

2, x, y, z

5, x, y, z

I am trying to write a script that will add the missing rows with the correct missing integer in the first column and and assign a 0 value to the other 3 columns, like;

1, x, y, z

2, x, y, z

3, 0, 0, 0

4, 0, 0, 0

5, x, y, z

What would be the easiest way to go about doing this?

[per isakson]

Does the entire file fit comfortably in memory (RAM)?

[Cameron Spooner]

yes

Answer 1

[Azzi Abdelmalek]

s=importdata('fic.txt')
out=zeros(s(end,1),4)
out(s(:,1),:)=s