Partial dates are currently only supported by the monkeypox instance. For SARS-CoV-2, the
month fields do not exist.
date field returns and the
dateTo parameters expect a string formatted as YYYY-MM-DD (e.g., 2022-05-29). There are however samples for which we do not know the exact date but only a partial date: e.g., only the year or the year and the month. In those cases, the
date is considered as unknown and will return a
null. That means that the query
dateFrom=2022-01-01 will not return samples for which we do not know the exact date but only that it is from May 2022.
To support partial dates, LAPIS additionally has the fields
month. They are returned by the
details endpoint and can be used as an aggregation field (e.g.,
fields=year,month is possible). Further, LAPIS offers
yearMonth has to be formatted as YYYY-MM. For example, the queries
yearMonthFrom=2022-05 will include all samples from May 2022.
Why is the query
dateFrom=2022-01-01 not returning samples from May 2022 that don’t have an exact date? The reason is that the following (desirable) property would be violated:
For t0 < t1: aggregated(dateFrom=t0) = aggregated(dateFrom=t0,dateTo=t1) + aggregated(dateFrom=t1+1) = sum(aggregated(dateFrom=t0,fields=date))