How to build the search fast?

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C Zeng
C Zeng 2012-12-24
Hi I have a database with cost assigned to over 500 zipcodes, that is, one zipcode has a corresponding cost. I want to build a function in matlab, that each time I have a zipcode it will return the cost. Is there a way to do it efficiently?
I have a plan to build a matrix, each row has a zipcode and a cost. I can input it but when I find it I need to go over all zipcodes to find the cost. Zipcodes are not consecutive by the way.
Thanks.

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Laura Proctor
Laura Proctor 2012-12-24
编辑：Laura Proctor 2012-12-24
If you have the Statistics Toolbox, you could use a dataset array.
% Create a sample dataset
x = dataset({(1:10)','ZipCodes'},{rand(10,1),'Cost'})
% Find the cost value associated with the ZipCode value of 5
x.Cost(x.ZipCodes==5)
Alternatively, you could use a map container, which allows you to just look up your cost by inputting the Zip Code value:
% Create a sample map container object
mapObj = containers.Map((1:10)',rand(10,1))
% Look up the cost associated with the ZipCode value of 5
mapObj(5)
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Laura Proctor
Laura Proctor 2012-12-24
Nonconsecutive values will work for both cases. I'm assuming that you already have the values in some sort of document which you should be able to import into MATLAB with the import tool (depending on the version of MATLAB you are using) as variables and then use those variables as inputs to whichever function you choose to use.
C Zeng
C Zeng 2012-12-25
You are right, I already have the data stored in Excel.

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Image Analyst
Image Analyst 2012-12-24
Why not just have a simple 500 by 2 numerical matrix to store the zip codes and the costs? Say you call it "zipCodeLookUpTable". Each row lists the zip code (in the first column) and the cost (in the second column). Then if you want to find the cost of a zip code, say it's called thisZipCode, find the row by looking in the first column, and then get the cost from the second column:
% Get the row where this zip code is located.
row = find(zipCodeLookUpTable(:,1) == thisZipCode);
% Get cost for this zip code.
cost = zipCodeLookUpTable(row, 2);
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Image Analyst
Image Analyst 2012-12-26
save() will save MATLAB data out to a disk file in a proprietary MATLAB format .mat file. It will not import data in an Excel file into MATLAB.

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