Making new matrix with specific rows

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Brandon
Brandon 2023-7-24
评论： dpb 2023-7-24
The following code as an example, how would I go about making a new separate table with only the rows with a specific value in a column?
ie: How would I go about making the new table with only 'ABC' in the first column?
I've tried the method of using a for loop and manually checking line by line but the file that I actually have to do this for is much larger and takes way too long so I was wondering if there's a faster way, maybe with ':'
A = {
'ABC' 1.0000 5.5000
'ABC' 2.0000 1.2000
'DEF' 3.0000 6.4000
'ABC' 4.0000 3.7000
'XYZ' 5.0000 3.6000
'PQT' 6.0000 9.6000};

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采纳的回答

Dyuman Joshi
Dyuman Joshi 2023-7-24
Ran in:
A = {
'ABC' 1.0000 5.5000
'ABC' 2.0000 1.2000
'DEF' 3.0000 6.4000
'ABC' 4.0000 3.7000
'XYZ' 5.0000 3.6000
'PQT' 6.0000 9.6000};
%Compare the 1st column of the char array/string 'ABC'
idx = strcmp(A(:,1),'ABC')
idx = 6×1 logical array
1 1 0 1 0 0
%Create the new array corresponding to the indices
B = A(idx,:)
B = 3×3 cell array
{'ABC'} {[1]} {[5.5000]} {'ABC'} {[2]} {[1.2000]} {'ABC'} {[4]} {[3.7000]}

更多回答（1 个）

dpb
dpb 2023-7-24
Use <logical indexing>, a basic MATLAB syntax/idiom. If this isn't something you're not already familiar with, I'd suggest reading through the <Language Fundamentals> section of the introductory help/documentation.
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Dyuman Joshi
Dyuman Joshi 2023-7-24
I strongly recommend you go through the free MATLAB Onramp tutorial to learn the essentials of MATLAB.
dpb
dpb 2023-7-24
While it seems like wasting time that could be coding; you'll progress towards the end goal far more effectively if you learn at least the rudiments of the language (and its idiosyncracies) first; the time spent either in the "Getting Started" or the "On Ramp" tutorials will pay back the investment many times over.

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