Insert new row with values in a table before specific values

Hey,

I have a table with 3 columns containing the following values:

Now I want to insert a new row with (0,0,0) everytime WP1 hits 0 before that, so that the new table looks like that:

What is an efficient way to do that?

Thanks for your help!

Answer 1

[Yazan]

WP1 = [0 145 169 1693 1708 2729 0 48];
WP2 = [145 169 1693 1708 2729 2779 48 1382];
WC = [0 1 1 1 1 0 0 1];

dat = [WP1', WP2', WC'];

T = table(WP1', WP2', WC', 'VariableNames', {'WP1', 'WP2', 'WC'});
disp(T)

    WP1     WP2     WC
    ____    ____    __

       0     145    0 
     145     169    1 
     169    1693    1 
    1693    1708    1 
    1708    2729    1 
    2729    2779    0 
       0      48    0 
      48    1382    1 

idx = find(T.WP1 == 0);
idx = idx + (0:length(idx)-1)';
Idx = true(size(WP1') + [length(idx) 0]);
Idx(idx) = false;

dat2 = zeros(size(dat) + [length(idx), 0]);
dat2(Idx, :) = dat;

T2 = table(dat2(:,1), dat2(:,2), dat2(:,3), 'VariableNames', {'WP1', 'WP2', 'WC'});
disp(T2)

    WP1     WP2     WC
    ____    ____    __

       0       0    0 
       0     145    0 
     145     169    1 
     169    1693    1 
    1693    1708    1 
    1708    2729    1 
    2729    2779    0 
       0       0    0 
       0      48    0 
      48    1382    1 

[Lukas Netzer]

ty!

Answer 2

[Peter Perkins]

It is possible to just use tabular subscripting to insert these rows. This is kind of old school MATLAB. Don't know if it is easier or harder to understand.

>> WP1 = [0; 145; 169; 1693; 1708; 2729; 0; 48];
>> WP2 = [145; 169; 1693; 1708; 2729; 2779; 48; 1382];
>> WC = [0; 1; 1; 1; 1; 0; 0; 1];
>> T = table(WP1, WP2, WC)
T =
  8×3 table
    WP1     WP2     WC
    ____    ____    __
       0     145    0 
     145     169    1 
     169    1693    1 
    1693    1708    1 
    1708    2729    1 
    2729    2779    0 
       0      48    0 
      48    1382    1 

Create an index vector that puts existing rows at their new locations.

>> n = height(T);
>> i = (1:n)';
>> incr = zeros(size(i));
>> incr(j) = 1;
>> i2 = i + cumsum(incr)
i2 =
     2
     3
     4
     5
     6
     8
    10
    11

Create an index vector that puts the inserted rows at their new locations.

>> j = find(T.WC == 0);
>> incr = ones(size(j)); incr(1) = 0;
>> j2 = j + cumsum(incr)
j2 =
     1
     7
     9

Add a row at the end, merge the index vectors, and use that to insert copies of the new end row into the right places.

>> T{end+1,:} = [0 0 0];
>> [~,k] = sort([i2; j2]);
>> k(j2) = n+1;
>> T = T(k,:)
T =
  11×3 table
    WP1     WP2     WC
    ____    ____    __
       0       0    0 
       0     145    0 
     145     169    1 
     169    1693    1 
    1693    1708    1 
    1708    2729    1 
       0       0    0 
    2729    2779    0 
       0       0    0 
       0      48    0 
      48    1382    1