How I delete one row and one column of a matrix?

Question

I think the title says it all. I am looking for a function f[A_matrix, r_Integer, c_Integer] that will return the matrix A with the row r and column c deleted. I know how to delete rows but how about columns?

Thanks, I appreciate

I tried using the Delete function, eg Delete[A,{2}] deletes the second row — Georgy, Feb 24 '23 at 15:34
Does this answer your question? Correct way to remove matrix columns? Also: How to delete arbitrary numbers of columns from a matrix in mathematica — Domen, Feb 24 '23 at 15:40

rhermans · Answer 1 · 2023-02-24T15:55:36.920

6

You are after Drop

Data example

MatrixForm[
    matrx=Outer[Row@*List, CharacterRange["A", "E"], Range[5]]
]

Now you can do Drop[matrix, {row},{column}]

MatrixForm[
     Drop[matrx, {3},{2}]
]

If you want to define your function

f[a_List?MatrixQ, row_Integer, column_Integer] := Drop[a, {row},{column}]

edited Feb 24 '23 at 15:55

answered Feb 24 '23 at 15:39

rhermans

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score 5 · Answer 2 · answered Feb 24 '23 at 15:37

5

(mat = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}}) // MatrixForm

Mathematica graphics

del[mat_?MatrixQ, col_Integer?(Positive), row_Integer?(Positive)] := 
 Module[{m = mat},
  m[[All, col]] = Sequence[];
  m[[row]] = Sequence[];
  m
  ];

Now

del[mat, 1, 1] // MatrixForm

Mathematica graphics

del[mat, 2, 2] // MatrixForm

Mathematica graphics

answered Feb 24 '23 at 15:37

Nasser

143,286
11
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359

1

You can also assign to Nothing instead of Sequence[] – Gustavo Delfino Feb 24 '23 at 15:38
@GustavoDelfino, yes, that works also. – Nasser Feb 24 '23 at 15:39
Great guys, I didn't know about this "All" thing, thank you! – Georgy Feb 24 '23 at 15:40

How I delete one row and one column of a matrix?

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