Guess whether fold change values are on a log2 or linear scale

Shinyngs stores fold changes internally as signed linear values (the ratio of the two conditions, with an absolute magnitude of at least 1 and the sign indicating direction - see fold_change), so a value strictly between -1 and 1 is only possible on a log2 scale (e.g. a log2 fold change of 0.5 is a ~1.4-fold change). log2 fold changes are also typically small and symmetric around zero, while linear fold changes can have very large magnitudes for the same effect size (e.g. a 1000-fold change is a log2 fold change of ~10).

Usage

guess_foldchange_scale(values, log2_magnitude_limit = 15)

Arguments

values

Numeric vector of fold change values (NAs and non-finite values are ignored).

log2_magnitude_limit

Values with an absolute magnitude greater than this are considered implausible for a log2 fold change (default 15, corresponding to a ~32,000-fold change).

Value

One of "log2", "linear" or "ambiguous".

Examples

guess_foldchange_scale(c(-2.1, 0.3, 1.8, -0.05))
#> [1] "log2"
guess_foldchange_scale(c(-8, 2, 45, -120))
#> [1] "linear"
guess_foldchange_scale(c(-2, 3, 5, -8))
#> [1] "ambiguous"