How to get values from a column based on the values of other columns?
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Hi,
I ordered a set of data as in the example below:
A B C D E F G J
,1985,04,10,1800,4,140,1, 2.0,
,1985,04,11,0900,4,999,1, 0.0,
,1985,07,09,0300,4,999,1, 0.0,
,1985,04,11,2100,4,020,1, 5.0,
,1987,03,03,1000,4,360,1, 10.0,
,1987,03,03,1100,4,360,1, 10.0,
,1987,01,03,0700,4,360,1, 8.0,
,1987,01,03,0900,4,360,1, 7.0,
,1987,03,03,1200,4,360,1, 10.0,
,1987,03,03,1300,4,360,1, 10.0,
,1985,07,09,1500,4,180,1, 10.0,
,1985,07,09,1800,4,180,1, 11.0,
,1985,07,10,0600,4,160,1, 3.0,
,1985,07,10,1000,4,180,1, 4.0,
,1985,04,11,1500,4,360,1, 9.0,
,1985,04,11,2000,4,050,1, 5.0,
,1985,07,10,1200,4,180,1, 5.0,
,1985,07,10,1500,4,180,1, 6.0,
,1987,01,03,0600,4,360,1, 8.0,
,1987,01,03,1100,4,360,1, 6.0,
,1985,07,09,0600,4,999,1, 0.0,
,1985,07,09,1200,4,180,1, 6.0,
,1987,01,03,1300,4,360,1, 6.0,
,1987,01,03,1600,4,360,1, 7.0,
,1987,01,03,1900,4,360,1, 6.0,
,1987,03,03,0500,4,020,1, 8.0,
,1987,03,03,0900,4,360,1, 10.0,
,1987,01,03,1400,4,320,1, 5.0,
,1987,03,03,1500,4,360,1, 10.0,
I want to create an array with the values in column "J" based on the values in column "B". . For example the vector Z should contain only the values of "J" that are on the same row with the value "01" in column "B", vector X only the "03" and so on ...
Thanks in advanace for the help and suggestions.
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采纳的回答
Michael Haderlein
2014-8-27
Are A...J cell arrays with strings or numeric arrays?
If you have numbers, this should do the job:
Z=J(B==1);
If it's cell arrays with strings, you need:
Z=J(strcmp(B,'01'));
Best regards,
Michael
更多回答(1 个)
Joseph Cheng
2014-8-27
编辑:Joseph Cheng
2014-8-27
you can use == to find the rows for each B value. here is an example of an implementation
uB = unique(MatAnsExample(:,2));
for ind = 1:length(uB)
Result(ind).B = uB(ind);
Result(ind).J = MatAnsExample(MatAnsExample(:,2)==uB(ind),8);
end
here i find each unique instance of values within column B. then with the for loop i store the current B in the Result structure as well as the values of J that correspond with that B. to do this i generate the logical mask of when column B is equal to the B in question.
4 个评论
Joseph Cheng
2014-8-27
so if you run my code lets say with an adaptation
uB = unique(MatAnsExample(:,2));
for ind = 1:length(uB)
Result(ind).B = uB(ind);
Result(ind).J = MatAnsExample(MatAnsExample(:,2)==uB(ind),8);
disp(['For a B of: ' num2str(uB(ind)) ' the J column are: ' num2str(Result(ind).J')]);
end
you get the results
For a B of: 1 the J column are: 8 7 8 6 6 7 6 5
For a B of: 3 the J column are: 10 10 10 10 8 10 10
For a B of: 4 the J column are: 2 0 5 9 5
For a B of: 7 the J column are: 0 10 11 3 4 5 6 0 6
you get the examples you just wrote. so instead of using individual variables Z, X, Y, etc. for each value of B. I am storing it as Result(N) where N from 1 to the number of unique instances within the B column. So to get the Z, X, etc. variable you can simply just type in Result(1).J instead. I also just put it in this form as i don't know what you are doing. The Right side of the equation is what you should be interested in and not the left side. The left side is for you to determine.
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