How to insert a row in a matrix

Question

Raheema Syed 2019-2-19

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评论： John 2022-12-21

I have a 31x 12 matrix, after the 11th row i want to insert a row matrix with zero values. so that i can make it 32x12 matrix.

how am i supposed to insert a zero row matrix after 11th row

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Answer 1

Adam Danz 2019-2-19

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编辑：Adam Danz 2019-2-25

在 MATLAB Online 中打开

Here's an example.

data = rand(31,12);                                   % your original matrix 
newRow = zeros(1,size(data,2));                       % row of 0s
newData = [data(1:11, :); newRow; data(12:end, :)]    % your updated matrix

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John 2022-12-21

This also works:

% Adding text to the middle of a text file.

file = ["I have a 31x 12 matrix,";" after the 11th row i want to insert ";...

"a row matrix with zero values.";"so that i can make it 32x12 matrix."];

Insert_string = "The quick brow fox";

i = 2;

file = [file(1:i,:); Insert_string; file(i+1:end, :)];

file =

5×1 string array

"I have a 31x 12 matrix,"

" after the 11th row i want to insert "

"The quick brow fox"

"a row matrix with zero values."

"so that i can make it 32x12 matrix."

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Answer 2

Jorge Fonseca 2022-6-22

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Hi Adam,

What if the "data" table as variable names? I have a table that I imported from Excel with variable names and i can add a row of zeros.

Regards

Jorge

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Adam Danz 2022-6-22

在 MATLAB Online 中打开

Here's a demo that starts with the imported table. For simplicity, I used numeric data for all table variables. When you're appending rows to a table, the variable types within each column may not change.

T = array2table(randi(9,5,4))
T = 5×4 table
    Var1    Var2    Var3    Var4
    ____    ____    ____    ____

     9       9       5       4  
     4       1       1       2  
     2       5       3       3  
     3       6       5       4  
     2       2       8       8  

Option 1: Add a row of zeros using vertical concatination

% Convert the rows of 0s to a table using the same variable names as
% original table. 
T0 = array2table(zeros(1,width(T)),'VariableNames', T.Properties.VariableNames)
T0 = 1×4 table
    Var1    Var2    Var3    Var4
    ____    ____    ____    ____

     0       0       0       0  
 
% Concatinate tables
T2 = [T; T0]
T2 = 6×4 table
    Var1    Var2    Var3    Var4
    ____    ____    ____    ____

     9       9       5       4  
     4       1       1       2  
     2       5       3       3  
     3       6       5       4  
     2       2       8       8  
     0       0       0       0  

Option 2: Add a row of zeros using indexing

T{end+1,:} = zeros(1,width(T))
T = 6×4 table
    Var1    Var2    Var3    Var4
    ____    ____    ____    ____

     9       9       5       4  
     4       1       1       2  
     2       5       3       3  
     3       6       5       4  
     2       2       8       8  
     0       0       0       0  

Now you can move the row(s) of added data to some other row(s) in the table. This example moves the row of 0s to row 3 of the table.

T = T([1,2,end,3:end-1],:)
T = 6×4 table
    Var1    Var2    Var3    Var4
    ____    ____    ____    ____

     9       9       5       4  
     4       1       1       2  
     0       0       0       0  
     2       5       3       3  
     3       6       5       4  
     2       2       8       8  