For a dataset as returned by get_xg3,
determine for each location the available multi-year XG3 series.
The function is called by eval_xg3_series.
Contrary to eval_xg3_series, it lists the member years of
each series as separate lines.
Note that 'years' in this context always refers to hydroyears.
extract_xg3_series(data, xg3_type = c("L", "H", "V"), max_gap, min_dur)
| data | An object returned by |
|---|---|
| xg3_type | Character vector of length 1, 2 or 3.
Defines the types of XG3 which are taken from |
| max_gap | A positive integer (can be zero). It is part of what the user defines as 'an XG3 series': the maximum allowed time gap between two consecutive XG3 values in a series, expressed as the number of years without XG3 value. |
| min_dur | A strictly positive integer. It is part of what the user defines as 'an XG3 series': the minimum required duration of an XG3 series, i.e. the time (expressed as years) from the first to the last year of the XG3 series. |
A tibble with variables:
loc_code: see get_locs
xg3_variable: character; see Details
hydroyear: each member year of a series is listed separately
series: series ID, unique within loc_code
series_length: series duration, i.e. from first to last year
An XG3 series is a location-specific, multi-year series of
LG3, HG3 and/or VG3 variables
and is user-restricted by max_gap (maximum allowed number of empty
years between 'series member' years) and
min_dur (minimum required length of the series).
Further, given a dataset of XG3 values per year and location, XG3 series are
always constructed as long as possible given the aforementioned
restrictions.
For one location and XG3 variable, more than one such XG3 series may be
available, which implies that those XG3 series are separated by more years
than the
value of max_gap.
The function returns the available XG3 series in the dataset for each
site and XG3 variable, and
numbers them for each site as 'prefix_series1', 'prefix_series2' with the
prefix being the value of xg3_variable.
The column xg3_variable in the resulting tibble
stands for the XG3 type + the vertical CRS (see get_xg3)
to which a series belongs.
xg3_variable is restricted to the requested XG3 types (LG3, HG3
and/or VG3) via the xg3_type argument, but adds an extra level
"combined" whenever the combination of data (which may have
both
vertical CRSes) and xg3_type implies more than one requested
variable.
This 'combined' level defines an XG3 series as an XG3 series where each
'member' year has all selected XG3 variables available.
if (FALSE) { watina <- connect_watina() library(dplyr) mylocs <- get_locs(watina, area_codes = "KAL") mydata <- mylocs %>% get_xg3(watina, 1900) mydata %>% arrange(loc_code, hydroyear) mydata %>% extract_xg3_series(xg3_type = c("L", "V"), max_gap = 2, min_dur = 5) # Disconnect: dbDisconnect(watina) }