Remove rows from a string array that correspond to rows being thresholded in a separate numeric matrix

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Jordan 2021-7-7

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评论： Cris LaPierre 2021-7-7

I have a string array and a separate numeric matrix. The string array is one column with many rows and the numeric matrix is two columns with many rows (the same number of rows as the string array). I want to threshold some of the rows of the numeric matrix, but if a row is removed from the numeric matrix I want the corresponding row number to be removed from the string array. For example, remove any rows where the value is < 0.05 in both columns of the numeric matrix. If rows 2,3,4 meet this condition in the numeric array then remove those rows from the string array as well. Thank you.

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Answer 1

Cris LaPierre 2021-7-7

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Use an index to capture the rows that meet your criteria, and then use that index to delete the corresponding rows from both arrays.

txt = ["A";"B";"C"];
num = [1 2; 3 4; 5 6];
% find rows that meet criteria
ind = num(:,2)==4;
% remove rows from string array and matrix
txt(ind) = []
txt = 2×1 string array
    "A"
    "C"
num(ind,:) = []
num = 2×2
     1     2
     5     6

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Jordan 2021-7-7

What if I need the criteria to be met across multiple columns? How would I index the rows that meet that criteria? For example, index rows whose elements are equal to 4 in column 1 and 2?

Cris LaPierre 2021-7-7

在 MATLAB Online 中打开

Just add additional criteria to your expression. In this case, none of the rows meet both criteria, so nothing is removed.

txt = ["A";"B";"C"];
num = [1 2; 3 4; 5 6];
% find rows that meet criteria
ind = num(:,2)==4 & num(:,1)==4;
% remove rows from string array and matrix
txt(ind) = []
txt = 3×1 string array
    "A"
    "B"
    "C"
num(ind,:) = []
num = 3×2
     1     2
     3     4
     5     6