TFQA: Tools for Quantitative Archaeology
     kintigh@tfqa.com   +1 (505) 395-7979

TFQA Home
TFQA Documentation
TFQA Orders
Kintigh (ASU Directory)

RANDPT: Generate Random Point Distributions

Distribution Shape: [C]ircular or [R]ectangular {R} ?

Indicates the shape of the limits of the distribution. Points will not eb generated outside the limits. More complex shapes are not allowed.

Distribution Diameter {20.0} ?
X Coord, Center {10.0} ?
Y Coord, Center {10.0} ?

or

Xmax {0.0} ?
Ymin ?
Ymax ?

      Define the distribution limits by diamter and center or corner coordinates.

Random Generator Seed {0} ?

      Seed the Random Number Generator.

[N]umber or [D]ensity of Random Points to be Specified {N} ?

      The program will generate either a fixed number of points or calculate a number of points based on the density in points per square unit based on the site size.

Number of Points ?

[C]entered or Contagious Around [S]eeds

      "Center" generated points in a single cluster centered on the distribution limits. "Contagious" establishes a number of random seeds around which points are clustered. Use contagious to produce a patchy distribution. Use Center for a simple random distribution.

Number of Seeds ?

Use Cluster Seeds as Points ?

      Choose whether or not the cluster seeds will count as points. Otherwise they will be invisible.

Size of Contagious Radius or Stddev ?

      A parameter that specifies the cluster “size” in the input units. For all but Normal (below) this specifies a radius. For Normal it specifies the number of units associated with 1 std.

Density Distribution Model

    [U]niform [H]emisphere [C]onic [S]inusoid [N]ormal {N} ?

Centered distributions act like seeded distributions with a single seed at the center and a seed radius the same as distribution limit radius (circular distributions) or the half the width of the limit (rectangular distributions). For contagious distributions: a Uniform model provides for equal probability for all points within the radius; a Hemispheric model provides that the probabilities at a given distance from the seed will fall off from a maximum at the seed to 0 at the edge with intermediate distributions following a hemispheric model (relatively slow falloff from the center); a Conic distribution has probabilities fall off linearly from the center to the edge; a Siusoidal model follows a sine curve (a rapid falloff from the center); a Normal model has probabilities dictated by the normal model (e.g., aproximately 2/3 within 1 seed radius and 95% within 2 seed radii). The program picks a tentative random point and effectivly decides whether to place the point based on the sum of the probabilities associated with each seed.

100

      Shows  program progress.

Write Coordinates {Y} ?

      If the plot looks satisfactory write the coordinates to a file. An answer of no will produce a new plot.

Output File {.ADF} ?

      Output file name.

Plot on Screen {Y} ?

      Show a schematic screen plot? Hit any key to end display.

RANDOM WALK

Input File may have any number of pairs of X, Y coordinates

Input file of Original Point Coordinates {.ADF} ?

Random Generator Seed (0 to set from clock) {0} ?

Output file of Random Walked Point Coordinates {.OUT} ?

Steplength is uniformly distributed between 0 and maximum specified

Maximum, Step length {1.0}

Number of Random Walk Steps {1}

xxx Points processed

Plot on Screen {Y} ?

SAMPLE PROGRAM OUTPUT

      For 100 points around 3 clusters in a 1x1 square, Sinusoidal distribution.

100 #Points# 2 #Coordinates#
# Site Corners   0.0000  0.0000,   1.0000  1.0000;  Area     1.00 #
#Density: 100.0000;  Model S;  Random Seed: 271977474 #
# Radius or S.D.  0.1000;  Cluster Seeds 3 #
    0.4324    0.3920
    0.1533    0.9733
    0.4166    0.3819
    0.3809    0.4138
    0.3686    0.4100
    0.0190    0.8881
...   
    0.2131    0.9706

Page Last Updated: 21 June 2022