Break a spectrum into segments when one or more wide masks exist

Source: R/break_spectrum.R

Break a spectrum into segments when one or more wide masks (i.e. sequences of many consecutively-masked pixels) exist. The spectrum can be polarized or unpolarized. When the spectrum is polarized, the set of masked spectral pixels used to define the spectrum's segmentation is taken to be the union set of pixels that are masked for any of the \(IQU\) Stokes parameters. Note that denoise_spectrum() calls break_spectrum() internally. So while break_spectrum() is an exported function, it typically does not need to be called directly.

break_spectrum(df, break_at = 10L, min_pix_segment = 10L)

Arguments

df

A tibble that includes a column titled "wavelength" and one or more columns with names ending in "mask", e.g. c("I_mask", "Q_mask", "U_mask"). The values of the mask columns should be equal to 0 (or FALSE) for unmasked pixels and nonzero (or TRUE) for masked pixels.
break_at

The minimum number of consecutively-masked spectral pixels that will trigger a break in the spectrum. Defaults to break_at = 10.
min_pix_segment

After the segmentation procedure is complete, the resulting segments are examined to ensure that each is sufficiently long for a non-trivial/well-defined denoising analysis. In particular, any segment that has fewer than min_pix_segment unmasked spectral pixels is discarded. Defaults to min_pix_segment = 10.

Value

A list of tibbles, with one for each segment of the segmented spectrum. Masked rows are now dropped and each tibble in the list has the same format as the input df, minus the mask columns.

See also

denoise_spectrum()

Examples

library(dplyr)

data(polarized_spectrum_WR_star)

wavelength <- seq(
  from = sci$axDat$crval[1],
  by = sci$axDat$cdelt[1],
  length = sci$axDat$len[1]
) %>%
  tibble::as_tibble_col(column_name = "wavelength")

flux <- as_tibble(sci$imDat) %>%
  rename_with(function(.cols) c("I", "Q", "U"))

variance <- as_tibble(var$imDat) %>%
  select(1:3) %>%
  rename_with(function(.cols) c("I_var", "Q_var", "U_var"))

mask <- as_tibble(bpm$imDat) %>%
  rename_with(function(.cols) c("I_mask", "Q_mask", "U_mask"))

df <- bind_cols(wavelength, flux, variance, mask)

df_list <- break_spectrum(df)