Description Usage Arguments Details References Examples
Compute the Time Allocation at Depth (TAD) index of a dive
1 2 3 4 5 6 7 8 9 10 11 12 13 | time_at_depth(x, vs = Inf, fs = NULL, ...)
## Default S3 method:
time_at_depth(x, vs = Inf, fs = NULL, ...)
## S3 method for class 'tdr'
time_at_depth(x, vs = Inf, ...)
## S3 method for class 'bsm'
time_at_depth(x, vs = Inf, ...)
## S3 method for class 'ses'
time_at_depth(x = ind(), vs = Inf, ...)
|
x |
input data. Can be a numeric vector of depth records
(then sampling frequency should be provided), a data frame with time and depth
as columns 1 & 2 or some |
vs |
Maximum vertical speed achievable. |
fs |
Sampling frequency (in Hz). Optional if a full time sequence is provided. |
... |
|
The index takes values from 0 for a dive where the maximum of time was spent
at the minimum depth, to 0.5 for "V"
shaped dives and 1
for "U"
shaped dives.
"ses"
and "tdr"
methods assume that time and depth information
respectively occupy the first and second columns of the tdr
tables.
Fedak, M. A., Lovell, P. and Grant, S. M. (2001). Two Approaches to Compressing and Interpreting Time-Depth Information as as Collected by Time-Depth Recorders and Satellite-Linked Data Recorders. Marine Mammal Science 17, 94–110.
1 2 3 4 5 6 7 8 9 10 11 12 | data(exses)
bsm_6pts <- tdrply(brokenstick, 1:2, obj = exses)
# These 4 lines return the same result
tad_highres <- tdrply(time_at_depth, 2, obj = exses, vs = 2, fs = 1)
tad_highres <- tdrply(time_at_depth, 1:2, obj = exses, vs = 2)
tad_highres <- sapply(bsm_6pts, time_at_depth, vs = 2) # "data" slot is used
exses$stat$tad <- tad_highres <- time_at_depth(exses, vs = 2)
# When the "data" slot is not available
tad_lowres <- sapply(eco.mem(bsm_6pts), time_at_depth, vs = 2) # "data" slot is not used
plot(tad_highres, tad_lowres) ; abline(0, 1, col = "red", lwd = 3)
plot(tad ~ time, exses$stat)
|
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