How to calculate or approximate the median of a list without storing the list

Question

I\'m trying to calculate the median of a set of values, but I don\'t want to store all the values as that could blow memory requirements. Is there a way of calculating or ap

Answer 1

I don't think it is possible to do without having the list in memory. You can obviously approximate with

• average if you know that the data is symmetrically distributed
• or calculate a proper median of a small subset of data (that fits in memory) - if you know that your data has the same distribution across the sample (e.g. that the first item has the same distribution as the last one)