get_features_3d: Computes event-features

In sevvandi/eventstream: Streaming Events and their Early Classification

Computes event-features

Description

This function computes event features of 3D events.

Usage

get_features_3d(dat.xyz, res.cluster, normal.stats, win_size, tt)

Arguments

dat.xyz	The data in a cluster friendly format. The first three columns have t,x and y positions with the fourth column having the pixel value of that position.
res.cluster	Cluster details from dbscan.
normal.stats	The background statistics, output from stats_3d.
win_size	The window length of the moving window model.
tt	Related to event ages. For example if tt=10 then the event ages are 10, 20, 30 and 40.

Value

An Nx22x4 array is returned. Here N is the total number of events extracted in all windows. The second dimension has 30 features and the class label for the supervised setting. The third dimension has 4 different event ages : tt, 2tt, 3tt, 4tt. For example, the element at [10,6,3] has the 6th feature, of the 10th extracted event when the age of the event is 3tt. The features are listed below:

cluster_id	An identification number for each event.
pixels	The number of pixels of each event.
length	The length of the event.
width	The width of the event.
total_value	The total value of the pixels.
l2w_ratio	Length to width ratio of event.
centroid_x	x coordinate of event centroid.
centroid_y	y coordinate of event centroid.
centroid_z	z coordinate of event centroid.
mean	Mean value of event pixels.
std_dev	Standard deviation of event pixels.
slope	Slope of a linear model fitted to the event.
quad1	First coefficient of a quadratic model fitted to the event.
quad2	Second coefficient of a quadratic model fitted to the event.
sd_from_mean	Let us denote the 80th percentile of the event pixels value by x. How many standard deviations is x is away from the mean?

Examples

set.seed(1)
arr <- array(rnorm(12000),dim=c(40,25,30))
arr[25:33,12:20, 20:23] <- 10
# getting events
out <- get_clusters_3d(arr, thres=0.985)
mean_sd <- stats_3d(arr[1:20,1:6,1:8])
ftrs <- get_features_3d(out$data, out$cluster$cluster, mean_sd, win_size=40, tt=2 )

sevvandi/eventstream documentation built on May 16, 2022, 11:23 a.m.