How to get data from containers.Map and store to a new table then view the table

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Andrea Del Rosario 2019-1-11

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回答： Guillaume 2019-1-23

Hi there,

I have a code that reads an excel file, choose specific columns to view then deletes rows that contains NaN cell. Now I have a for loop and I have to use containers.Map so I can filter out the duplications of the data.

I understand that I can acces specific data in my map. but my problem now is that, I want to store the unique key and its value set to a new table. Then I want to be able to view the table with non duplicated data. After this I want to access that table to plot graphs. This is the code that I have at the moment.

%--FIND NaN ROWS THEN DELETE ENTIRE ROW
%imports data (.csv) file
PCBAllDataSet = readtable('testfile5.csv');
%imports the only columns needed
PCBRequiredCol = PCBAllDataSet(:,{'PcbTestID','PcbID','Verify12VInput','VerifyCurrentDraw'});
%remove row that contains NaN value
PCBRemoveNaNRow = rmmissing(PCBRequiredCol);
%--REMOVE (PCBID) ROW DUPLICATIONS
%create another table for keyset and valueset
%duplications will be removed as the table is made
newTable = containers.Map('KeyType','char','ValueType','any');
%forloop to assign key and value set on every row
for i = 1:size(PCBRemoveNaNRow,1)
    %stores PCBID Column as key 
    %char(table2cell) -> type table cast it to cell then cast again to match KeyType'char'
    keyID = char(table2cell(PCBRemoveNaNRow(i,2)));
    %current(i) row, 3rd column to end column
    valueSet = PCBRemoveNaNRow(i,3:end);
    %create new table to assign every key to a value set 
    newTable(keyID) = valueSet;
end

Can anyone please help me how to extract these unique and value set to a new table so I can view it as a table then access the table to do graphs? Please Help :(

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Andrea Del Rosario 2019-1-11

testfile5.csv

Here is the file

Peter Perkins 2019-1-23

It's not at all clear why you are using Map, and that's a lot of code to expect people to try to understand. If all you want to do is delete duplicate rows of a table, I suggest looking at the unique function.

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Answer 1

Guillaume 2019-1-23

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https://ww2.mathworks.cn/matlabcentral/answers/439258-how-to-get-data-from-containers-map-and-store-to-a-new-table-then-view-the-table#answer_357692

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I'm not sure Andrea is still interested in an answer as the question is fairly old now. As Peter said, if the purpose of the conversion to a map is purely to remove unique element, then it's a complete waste of time. Simply use unique:

[~, rowstokeep] = unique(PCBRemoveNaNRow.PcbID);  %possibly with the'stable' option
newTable = PCBRemoveNaNRow(rowstokeep, :)
%all done

Even the way the map is built is inefficient. There's no need for a loop:

map = containers.Map(PCBRemoveNaNRow.PcbID, mat2cell(PCBRemoveNaNRow, ones(1, height(PCBRemoveNaNRow)), width(PCBRemoveNaNRow)))

Converting that to a table can be done fairly simply:

values = map.Values;
newTable = vertcat(values{:})

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How to get data from containers.Map and store to a new table then view the table

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