shotGroups (version 0.1)

groupSpread: Spread measures of a single group of bullet holes

Description

Provides spread measures and their graphical representations for a single group of bullet holes.

Usage

groupSpread(xy, plots = TRUE,
            conversion = 'm2cm', dstTarget = 25)

Arguments

xy

a numerical (n x 2)-matrix with the (x,y)-coordinates of n points (1 row of coordinates per point).

plots

a logical value indicating whether diagrams should be shown.

conversion

how to convert the measurement unit for distance to target to that of the (x,y)-coordinates in MOA calculation. See getMOA.

dstTarget

a numerical value giving the distance to the target in MOA calculation. See getMOA.

Value

• A list with the results from the numerical analyses and statistical tests.
• sdXY
  standard deviations of x- and y coordinates in original measurement units and MOA.
• sdXYrob
  robust standard deviations of x- and y-coordinates in original measurement units and MOA (MCD algorithm).
• covXY
  covariance matrix of (x,y)-coordinates.
• covXYrob
  robust estimate of covariance matrix of (x,y)-coordinates (MCD algorithm).
• corXY
  correlation matrix of (x,y)-coordinates.
• corXYrob
  robust estimate of correlation matrix of (x,y)-coordinates (MCD algorithm).
• meanDistToCtr
  average distance from points to their center in original measurement units and MOA.
• maxPairDist
  maximum pairwise distance between points in original measurement units and MOA.
• groupWidth
  width of minimum bounding in original measurement units and MOA.
• groupHeight
  height of minimum bounding in original measurement units and MOA.
• minCircleRad
  radius for the minimum enclosing circle in original measurement units and MOA.

Details

In addition to the numerical results listed below, this function produces the following diagrams:

• a scatterplot of the (x,y)-coordinates together with group center, circle with average distance to center, and 95\%-confidence ellipse - the latter also based on a robust estimate for the covariance matrix
• a scatterplot of the (x,y)-coordinates together with the minimum bounding box, minimum enclosing circle, and maximum group spread
• a histogram for distances to group center including a nonparametric kernel density estimate

See Also

getDistToCtr, getMaxPairDist, getMinBBox, getMinCircle, getMOA, hist, kernel, covMcd,

Examples

xy  <- matrix(round(rnorm(200, 0, 5), 2), ncol=2)
res <- groupSpread(xy, conversion='m2cm', dstTarget=25)
names(res)
res$sdXYrob
res$corXY
res$meanDistToCtr
res$maxPairDist