how to take out a specific row out of matrix

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farfar
farfar 2018-7-20
回答： Image Analyst 2018-7-20
Hello I have this matrix :
a = [john 2016;john 2015;mike 2016;leo 2018]
I only need information from 2016 in second column, like:
n = [john 2016;mike 2016]
I am using this code but it does not work. any help ? Thank you !
b = [2016];
n = a(ismember(a(:,2),b),:);
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farfar
farfar 2018-7-20
编辑：farfar 2018-7-20
true. in the excel file, the first column is the name and the second is the numbers. but when i read it with xlsread, the matrix "a" in my workspace has only one column, (the numbers). it is not reading the names.
Image Analyst
Image Analyst 2018-7-20
You do NOT have that matrix. Since your whos statement (assuming you did what James told you to do) didn't show them as variables, they're probably strings you got from Excel, which means that (the badly-named) a and n would have to be cell arrays. But the best, most modern way to do this now is with a table, something like (untested):
t = readtable(filename);
rowsToExtract = t{:, 2} == 2016
t2016 = t(rowsToExtract, :)

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Image Analyst
Image Analyst 2018-7-20
Attach your workbook. This can probably be done with tables:
t = readtable(filename);
rowsToExtract = t{:, 2} == 2016
t2016 = t(rowsToExtract, :)

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