title: How to make an adjacency matrix from three time events in R
body: <p>I have data of fire events by type (human induced, natural, accidental), months (Jan, Feb....Dec), location and year (2010....,2017). There are hundreds of unique locations. I want to make an adjacency matrix by assuming that fire events of different locations are related if fire type is same and occurred in the same month of corresponding year. Is there easy way to do it in R. Thanks for you help. </p>