profoundSegimCompare: Compare the Bijective Similarity of Segim Maps

In asgr/ProFound: Photometry Tools

Compare the Bijective Similarity of Segim Maps

Description

Determines the fraction pixel agreement for different segim maps of the same image. The idea is this allows people to experiment with extraction settings, and easily compare the impact on properties for similar sources.

Usage

profoundSegimCompare(segim_1, segim_2, threshold = 0.5, cores = 1, ignoresky = TRUE)

Arguments

segim_1	Integer matrix; required, the first segmentation map of the image.
segim_2	Integer matrix; required, the second segmentation map of the image.
threshold	Numeric scalar; the bijective threshold to use. Setting this to 0.5 ensures results have to be unambiguous, but even 0.25 is effectively a certain match since it must mean no worse than 0.5x0.5 for the input fractions (at absolute worst there could be two such cases creating ambgiuity, but in reality that will basically never happen for a real image). Higher is obviously better, but setting too high might mean an unhelpfully small number of matches (since you are basically forcing yourself to only compare segments that agree really well, and ignoring the trickier cases).
cores	Integer scalar; number of cores to use.
ignoresky	When considering similarity, should disagreement about sky by ignored (TRUE) or considered (FALSE).

Details

The function does a bijective process where all segim_1 seg IDs are iterated over and table made of associated segim_2 values in those pixels. The same process is then done the other way round. The end result is two max(segID) x max(segID) matrices (seg1_in_seg2 and seg2_in_seg1) with all possible matches considered (in both cases the rows/x-axis are the reference segim and the cols/y-axis are the associated segim). These two matrices are then multiplies together to make a bijective product matrix (seg_bij) where bijective products above threshold are then extracted to form a best match table (tab_match)

Value

Output is a list with:

seg_bij	Numeric matrix; bijective product matrix of seg1_in_seg2 x transpose(seg2_in_seg1). Thus the rows/x-axis correspond to seg IDs in segim_1 and cols/y-axis correspond to seg IDs in segim_2.
tab_match	Data frame; table of best matches (i.e. those that are above threshold in seg_bij). Columns are segID_1 / segID_2 / rowID_1 / rowID_2, where the segID is the actualy segment value and rowID is the position for this segment in the segstats output (if ordered in the default manner of ascending segID).
seg1_in_seg2	Numeric matrix; dimensions max(segID) x max(segID) where position corresponds to segID and rows/x-axis are the reference segim_1 and the cols/y-axis are the associated segim_2.
seg2_in_seg1	Numeric matrix; dimensions max(segID) x max(segID) where position corresponds to segID and rows/x-axis are the reference segim_2 and the cols/y-axis are the associated segim_1.

Author(s)

Aaron Robotham

See Also

profoundMakeSegim

Examples

## Not run: 
image = Rfits_read_image(system.file("extdata", 'VIKING/mystery_VIKING_Z.fits',
  package="ProFound"))

profound = profoundProFound(image, skycut=1, pixcut=100, plot=TRUE)
profound2 = profoundProFound(image, skycut=5, plot=TRUE)

magimage(profound$segim, col=c(NA,hcl.colors(100)), magmap=FALSE)

testcomp = profoundSegimCompare(profound$segim, profound2$segim, threshold=0.7)

magimage(testcomp$seg_bij, col=c(NA,hcl.colors(100)), xlab='segID_1', ylab='segID_2')

magplot(profound$segstats[testcomp$tab_match$rowID_1,'mag'],
 profound2$segstats[testcomp$tab_match$rowID_2,'mag'],
 xlab='mag (ProFound 1)', ylab='mag (ProFound 2)')
abline(0,1)

## End(Not run)

asgr/ProFound documentation built on Feb. 10, 2024, 9:04 p.m.