profoundSegimNear: Segment Neighbour IDs

In ProFound: Photometry Tools

Description

Returns a data.frame of all nearby (default is touching) segments surrounding every segment in a provided segim.

Usage

profoundSegimNear(segim = NULL, offset = 1)

Arguments

segim	Integer matrix; a specified segmentation map of the image (required).
offset	Integer scalar; the distance to offset when searching for nearby segments.

Details

This function can be run by the user directly, but usually it is called from within a higher routine in the ProFound suite of objects detection functions.

Value

A data.frame of lists giving the segIDs of nearby segments for every segment. This is a slightly unusal structure to see in R, but it allows for a compact manner of storing uneven vectors of touching segmentss. E.g. you might have a massive segment touching 30 other segments and many segments touching none. Padding a normal matrix out to accommodate the larger figure would be quite inefficient.

segID	Segmentation ID, which can be matched against values in segim
nearID	An embedded list of segmentation IDs for nearby segments. I.e. each list element of nearID is a vector (see Examples for clarity).
Nnear	The total number of segments that are considered to be nearby.

Note

Due to the construction of the segmented curve-of-growth in ProFound you may have cases where the separation between segments is two or three pixels. Since these are very close to touching you might want to catch these close neighbours rather than strictly touching. By increasing offset to a larger number (2 or 3 in the cases above) you can flag these events.

Author(s)

Aaron Robotham

See Also

profoundProFound, profoundMakeSegim, profoundMakeSegimDilate, profoundMakeSegimExpand, profoundSegimStats, profoundSegimPlot

Examples

## Not run: 
image=readFITS(system.file("extdata", 'VIKING/mystery_VIKING_Z.fits', package="ProFound"))
profound=profoundProFound(image, skycut=1.5, magzero=30, verbose=TRUE)

#Look for nearby (in this case touching) neighbours

near=profoundSegimNear(profound$segim)

#Look at the first few rows (segIDs 1:5):

near[1:5,]

#To access the embedded vectors you have to use unlist:

unlist(near[3,2])

#We can check to see which segments are touching segID number 3:

profoundSegimPlot(image$imDat, profound$segim)
magimage(profound$segim==3, col=c(NA,'red'), add=TRUE)
magimage(matrix(profound$segim %in% unlist(near[3,2]), dim(profound$segim)[1]),
col=c(NA,'blue'), add=TRUE)

## End(Not run)

ProFound documentation built on Jan. 8, 2021, 5:37 p.m.