If one of the values is zero the result will be zero. The harmonic mean is a type of average a measure of the central location of the data. MAP mean average precision is the average of AP.
It is often appropriate when averaging rates or ratios for example speeds.
To calculate mAP we first have to calculate Precision Recall and IoU for each object. The mean method is useful to calculate the meanaverage of the given list of numbers. It is often appropriate when averaging rates or ratios for example speeds. What the formula is essentially telling us is that for a given query q we calculate its corresponding AP and then the mean of the all these AP scores would give us a single number called the mAP which quantifies how good.