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Ratio of an index value to its neighbouring years

Source: R/data-scenarios.R
peak_ratio.Rd

Quantifies a peak (or trough) in an index as the value in year divided by the mean of the neighbours. A ratio is unaffected by the level of the index, so it compares scenarios with different prediction grids.

Usage

peak_ratio(x, year, neighbours = c(year - 1, year + 1), group = NULL)

Arguments

x

An object from sdmTMB_data_scenarios() or sdmTMB_leave_out(), or a data frame with columns year, est and optionally a grouping column.

year

The year of the peak.

neighbours

The years to compare with. Default the years before and after year.

group

Name of the grouping column for a data frame. Default "scenario" for scenario objects and "id" for leave-out objects.

Value

A tibble with the group, peak (the index in year), neighbours (mean of the neighbouring years) and peak_ratio.

See also

sdmTMB_data_scenarios()

Author

Mikko Vihtakari

Examples

idx <- data.frame(year = 2000:2004, est = c(10, 11, 20, 12, 10))
peak_ratio(idx, year = 2002)
#>   .group peak neighbours peak_ratio
#> 1  Index   20       11.5    1.73913