Find similar values in a matrix

4 次查看（过去 30 天）
lsutiger1
lsutiger1 2016-2-2
编辑： lsutiger1 2016-2-2
I am currently working with large data sets, on the range of 500k-1m rows of data in any given matrix. (nx3)
I want to know how to sift through the rows of the matrix to see if any of the rows have the same values in them.
ex. [1 2 3; 2 3 4; 3 4 5; 4 5 6; 1 2 3; 5 6 7]
I want to remove the second [1 2 3] row, such that [1 2 3; 2 3 4; 3 4 5; 4 5 6; 5 6 7]
Can anyone help me with this?

请先登录，再回答此问题。

采纳的回答

Star Strider
Star Strider 2016-2-2
The unique function can help here:
A = [1 2 3; 2 3 4; 3 4 5; 4 5 6; 1 2 3; 5 6 7];
[Au,ia,ic] = unique(A, 'rows', 'stable');
RowIdxFreq = accumarray(ic, 1);
RowIdxFreq =
2
1
1
1
1
The ‘RowIdxFreq’ variable has the frequencies of the occurrences of the rows. Here, row #1 is repeated.
  7 个评论
显示 5更早的评论
Star Strider
Star Strider 2016-2-2
Without having your matrix to experiment with, I can only guess.
See if adding a cell reference (the ‘{}’ brackets) works:
atomPositions = unique(X{:},'rows','stable');
If you have a relatively ‘uncomplicated’ cell array, that should work. If unique still has problems, you might have to use sprintf to convert the numbers to strings before you do the operations in my code. (I assume ‘atom_names’ are already strings.)
lsutiger1
lsutiger1 2016-2-2
编辑：lsutiger1 2016-2-2
The matrix is a 2520x3 matrix, and yes, atom_names is a 2520x1 vector of strings. I tried converting it to strings using num2str, which did not work, because then I got a "dimension mismatch" error when num2str converted my matrix into a 2520x33 char. Will try to use sprintf.

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Characters and Strings 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by