find intersect of a column against another column and extracting rows

Question

liu James 2017-6-25

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/346192-find-intersect-of-a-column-against-another-column-and-extracting-rows

回答： Image Analyst 2017-6-25

I'm trying to compare two tables A & B and find intersections of the time within one column of A against the time column of B and then extract that row associated with that time in that column of A & B into another array/matrix in sequential order.

CUM='/Users/jl/Desktop/Test/rev2.xlsx';
xlsread(CUM);
date1=ans(:,1);
date2=ans(:,3);
CU1=ans(:,2);
CU2=ans(:,4);
A=[date1,CU1];
B=[date2,CU2];
C=intersect(A,B);

This is what I have and the function intersect (A,B) is only extracting rows that are the same in both columns. Is there another function that can do what I'm trying to do?

2 个评论
显示无隐藏无

Image Analyst 2017-6-25

You forgot to attach rev2.xlsx. And I'm not sure what you want. intersect() gives you the indexes where the number is common to both A and B. Then you can extract those rows from one or both matrices. Isn't that what you want?

liu James 2017-6-25

在 MATLAB Online 中打开

I've attached the file. For instance assume

D=[1,1;1,2;2,3;3,4;5,3]

this gives, and

D =

     1     1
     1     2
     2     3
     3     4
     5     3
F=[1,2;1,3;3,3;4,5]
F =
       1     2
       1     3
       3     3
       4     5

I want to extract and make this.

G=[1,1,2;1,2,3;3,4,3]

G =
       1     1     2
       1     2     3
       3     4     3

however, the intersect function intersect(D,F) would give me the list of numbers that are common in both arrays.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Image Analyst 2017-6-25

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/346192-find-intersect-of-a-column-against-another-column-and-extracting-rows#answer_271910

在 MATLAB Online 中打开

This will do that:

D=[1,1;1,2;2,3;3,4;5,3] 
F=[1,2;1,3;3,3;4,5]
commonNumbersInCol1 = intersect(D(:, 1), F(:, 1))
rowsInD = ismember(D(:, 1), commonNumbersInCol1)
rowsInF = ismember(F(:, 1), commonNumbersInCol1)
G = [D(rowsInD, :), F(rowsInF, 2)]

but what if there are not the same number of rows in both F and D? What if 1, and 3 occurred 3 times in D (like now), but 100 times in a different F? What then?