How to create Correlation matrix

[nvucic]

Hello,

I would like to use the RE2C method to combine the results of eQTL analysis conducted across multiple GTEx tissues using simple linear regression. The RE2C method is suitable for handling the correlation between samples from different tissues that might originate from the same individual. To utilize the RE2C method, a correlation matrix is required as input. I am interested in understanding how to generate this correlation matrix file for my analysis.

Best,
Nemanja