das_chop_condition: Chop DAS data - condition

In swfscDAS: Southwest Fisheries Science Center Shipboard DAS Data Processing

Chop DAS data - condition

Description

Chop DAS data into a new effort segment every time a specified condition changes

Usage

das_chop_condition(x, ...)

## S3 method for class 'data.frame'
das_chop_condition(x, ...)

## S3 method for class 'das_df'
das_chop_condition(
  x,
  conditions,
  seg.min.km = 0.1,
  distance.method = NULL,
  num.cores = NULL,
  ...
)

Arguments

x	an object of class das_df, or a data frame that can be coerced to class das_df. This data must be filtered for continuous effort sections; see the Details section below
...	ignored
conditions	the conditions that trigger a new segment; see das_effort
seg.min.km	numeric; minimum allowable segment length (in kilometers). Default is 0.1. See the Details section below for more information
distance.method	character; see das_effort. Default is NULL since these distances should have already been calculated
num.cores	see das_effort

Details

WARNING - do not call this function directly! It is exported for documentation purposes, but is intended for internal package use only.

This function is intended to be called by das_effort when the "condition" method is specified. Thus, x must be filtered for events (rows) where either the 'OnEffort' column is TRUE or the 'Event' column is "E"; see das_effort for more details. This function chops each continuous effort section (henceforth 'effort sections') in x into modeling segments (henceforth 'segments') by creating a new segment every time a specified condition changes. Each effort section runs from an "R" event to its corresponding "E" event. After chopping, das_segdata is called (with segdata.method = "maxdist") to get relevant segdata information for each segment.

Changes in the one of the conditions specified in the conditions argument triggers a new segment. One exception is if the event at which this condition change occurs is part of an event series, meaning one of several events in a row at the same lat/lon points (such as a PVNW event series). In this situation, the final event of the event series is considered the last event of the current effort segment, and thus also the start of the next effort segment.

Related, when multiple condition changes happen at the same lat/lon points, such as a "RPVNW" series of events at the beginning of the effort section. When this happens, no segments of length zero are created; rather, a single segment is created that includes all of the condition changes (i.e. all of the events in the event series) that happened during the series of events (i.e. at the same location). Note that this combining of events at the same position happens even if seg.min.km = 0.

In addition, (almost) all segments whose length is less than seg.min.km are combined with the segment immediately following them to ensure that the length of (almost) all segments is at least seg.min.km. This allows users to account for situations where multiple conditions, such as Beaufort and the visibility, change in rapid succession, for instance <0.1 km apart. When segments are combined, a message is printed, and the condition that was recorded for the maximum distance within the new segment is reported. See das_segdata, segdata.method = "maxdist", for more details about how the segdata information is determined. The only exception to this rule is if the short segment ends in an "E" event, meaning it is the last segment of the effort section. Since in this case there is no 'next' segment, this short segment is left as-is.

If the column dist_from_prev does not exist, the distance between subsequent events is calculated as described in das_effort

Value

List of two data frames:

• x, with columns added for the corresponding unique segment code and number

• segdata: data frame with one row for each segment, and columns with relevant data (see das_effort for specifics)

swfscDAS documentation built on Aug. 10, 2023, 9:06 a.m.