LightFM: When do I make preserve_rows=True

Question

In LightFM, the evaluation methods e.g. precision_at_k have a preserve_rows parameter with default value False. In what cases would I make it True?

Answer 1

In case some other bit of your code expected your score arrays to maintain their size. I wouldn't expect this to be common.

In most cases you just take a mean of the result.