merge_time function

Merge Events

Given two event data frames of neighboring stations $S_x$ and $S_y$ that consist of flow fluctuation events and computed metrics (see hydropeak::get_events()), the translation time indicated by the relation file as well as timeLag between these two stations is subtracted from $S_y$ and events are merged where matches according to differences allowed to timeLag can be found.

merge_time(
  Sx,
  Sy,
  relation,
  timeLag = c(1, 1, 1),
  TimeFormat = "%Y-%m-%d %H:%M",
  tz = "Etc/GMT-1"
)

Arguments

• Sx: Data frame that consists of flow fluctuation events and computed metrics (see hydropeak::get_events()) of an upstream hydrograph $S_x$.
• Sy: Data frame that consists of flow fluctuation events and computed metrics (see hydropeak::get_events()) of a downstream hydrograph $S_y$.
• relation: Data frame that contains the relation between upstream and downstream hydrograph. Must only contain two rows (one for each hydrograph) in order of their location in downstream direction. See the appended example data relation.csv or vignette for details on the structure. See get_lag() for further information about the relation and the lag between the hydrographs.
• timeLag: Numeric vector specifying factors to alter the interval to capture events from the downstream hydrograph. By default it is timeLag = c(1, 1, 1), this refers to matches within a time slot $\pm$ the mean translation time from relation. For exact time matches, timeLag = c(0, 1, 0) must be specified.
• TimeFormat: Character string giving the date-time format of the date-time column in the input data frame (default: "%Y-%m-%d %H:%M").
• tz: Character string specifying the time zone to be used for the conversion (default: "Etc/GMT-1").

Returns

Data frame that has a matched event at $S_x$ and $S_y$ in each row. If no matches are detected, NULL is returned.

Examples

Sx <- system.file("testdata", "Events", "100000_2_2014-01-01_2014-02-28.csv",
                  package = "hydroroute")
Sy <- system.file("testdata", "Events", "200000_2_2014-01-01_2014-02-28.csv",
                  package = "hydroroute")
relation <- system.file("testdata", "relation.csv", package = "hydroroute")
# read data
Sx <- utils::read.csv(Sx)
Sy <- utils::read.csv(Sy)
relation <- utils::read.csv(relation)
relation <- relation[1:2, ]

# exact matches
merged <- merge_time(Sx, Sy, relation, timeLag = c(0, 1, 0))
head(merged)

# matches within +/- mean translation time
merged <- merge_time(Sx, Sy, relation)
head(merged)