Hi, I have a correlation matrix of about 3000 items, i.e., a 3000*3000 matrix. For each of the 3000 items, I want to get the top 50 items that have the highest correlation with it (excluding itself) and generate a data frame with 3 columns like ("ID", "ID2", "cor"), where ID is those 3000 items each repeat 50 times, and ID2 is the top 50 correlated items with ID, and cor is the correlation of ID and ID2. I know I can use two for loops to do it but it is very time consuming considering the correlation matrix is generated for each month of the past 20 years. Is there a better way to do it? Regards, Richard
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