Calculate purity thresholds

Intermediate function used in get_purity to compute variance-based thresholds.

Usage

get_agilent_threshold(
  x,
  pos,
  weight = 1,
  noise_variance = NULL,
  noise_threshold = 0.005,
  lambdas
)

Arguments

x

A chromatographic matrix (timepoints × wavelengths).

pos

A length-3 integer vector c(apex, start, end) giving the row indices of the peak apex, left boundary, and right boundary in x.

weight

Scaling parameter affecting stringency of threshold. Defaults to 1.

noise_variance

Variance of noise.

noise_threshold

Threshold to define noise. Highest proportion of maximum absorbance. Defaults to 0.005.

lambdas

Wavelengths to include.

Value

Returns a vector of purity thresholds at each retention time index within the peak specified by pos.

References

Stahl, Mark. “Peak Purity Analysis in HPLC and CE Using Diode-Array Technology.” Agilent Technologies, April 1, 2003, 16. 5988-8647EN.pdf

Author

Ethan Bass

Examples

data(Sa_warp)
x <- Sa_warp[[1]]
pos <- c(37, 22, 51)
get_agilent_threshold(x, pos)
#>  [1] 0.08919129 0.04889951 0.02983187 0.00000000 0.00000000 0.00000000
#>  [7] 0.18706175 0.64143327 0.85443767 0.93649520 0.96786675 0.98059458
#> [13] 0.98603512 0.98835261 0.98907636 0.98863759 0.98678229 0.98243533
#> [19] 0.97297769 0.95181639 0.90252245 0.80466241 0.68708839 0.56780858
#> [25] 0.38645915 0.12893417 0.00000000 0.00000000 0.00000000 0.00000000