Convert confidence levels into z thresholds

Turn one or several confidence levels into the two-sided normal (z) thresholds they correspond to, rounded for readability. It is a convenience for writing the zscore color break scale (set_color_breaks) in the vocabulary you already use elsewhere — confidence levels — instead of remembering that 95 % is 1.96. The scale itself always stores plain z magnitudes, so conf_level_to_z(0.95) and 1.96 are strictly interchangeable.

Usage

conf_level_to_z(conf_level, digits = 2)

Arguments

conf_level

A numeric vector of confidence levels, each between 0 and 1 (e.g. c(0.95, 0.99)).

digits

Number of digits to round to (default 2). Rounding keeps color legends readable ("+1.96" rather than "+1.959964"); pass Inf for the exact values.

Value

A numeric vector of positive z thresholds, the same length as conf_level.

Examples

conf_level_to_z(c(0.95, 0.99))
#> [1] 1.96 2.58

# the default `zscore` break scale (color = "contrib", color_signif = "guaranteed_effect")
conf_level_to_z(c(0.95, 0.99, 0.9999, 1 - 2e-9))
#> [1] 1.96 2.58 3.89 6.00

# \donttest{
set_color_breaks(zscore = conf_level_to_z(c(0.95, 0.999)))
set_color_breaks(zscore = c(2, 3, 4, 6))  # or plain z values, identically
# }