whichtank: Which Tanks are Used during a Dive

Description

Determine which tank of breathing gas is used at each time point during a dive.

Usage

whichtank(d)
whichtank(d) <- value

Arguments

The dive (an object of class "dive").

value

Vector of integers or character strings identifying which tank of breathing gas is used at each time point.

Value

The value of whichtank(d) is a vector of integers or character strings.

Details

An object of class "dive" represents a scuba dive, including information about depth, time and gas breathed at each stage of the dive. These objects are created by the function dive.

A dive object has a tank list which is a list of the tanks of breathing gas that were used (or were available to be used) during the dive. The function tanklist returns this list.

The selection of tanks, i.e. which tank is actually used at each stage of the dive, is specified by whichtank. The command whichtank(d) returns a vector of integers or character strings, identifying which tank in the tank list is in use at each waypoint during the dive. That is, whichtank(d)[i] is the tank in use at the ith waypoint during the dive.

The command whichtank(d) <- value will change the selection of tanks used at each stage during the dive. Here value should be a vector of integers or character strings identifying tanks in the tank list, and the length of value should be equal to the length of the vectors depths.dive(d) and depths.dive(d).

A common use of whichtank is to specify that a particular gas should be used only in a particular range of depths. This is done by applying ifelse to depths.dive as shown in the Examples.

Examples

Run this code

   # tanks are numbered
   d <- dive(air, c(30,40), 6, nitrox(0.5), c(6,3), c(3,3))
   d
   tanklist(d)
   whichtank(d)
   # change choice of tank at 6 metre deco stop
   # The Hard Way:
   whichtank(d) <- c(1,1,1,1,1,2,2,2)
   d

   # The Snazzy Way:
   # if shallower than 3 metres, then tank 2, else tank 1
   whichtank(d) <- ifelse(depths.dive(d) <= 3, 2, 1)
   d

   # tanks with names
   dd <- dive(tanklist=list(travel=trimix(0.18, 0.5), deco=nitrox(0.8)),
             tank="travel", c(30,40), c(20, 10), 9, tank="deco",
             c(9,10), c(6,5), c(3,5))
   dd
   # if shallower than 6 metres, then deco gas, else travel gas
   whichtank(dd) <- ifelse(depths.dive(dd) <= 6, "deco", "travel")
   dd