Summed batch mAP score equal to epoch mAP score?


I want to calculate mAP score for each epoch. However, keeping the each prediction in memory for an entire epoch is not possible on my machine. So I was wondering if I could simply compute the mAP for the predicitions of each batch and sum them up at the end of the epoch.
Is that possible or will the result be wrong if I do that?

Thanks in advance!