MapCalc Operations (draft
6/00)
…advanced grid-based analysis of mapped data
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Analyze-- Creates a map of the simple or weighted average,
standard deviation and other descriptive statistics of two or more maps.
Clump-- Assigns new values to contiguous groups of cells within
each map category.
Cluster-- Identifies spatial groupings (clusters of similar data)
from a stack of maps.
Compare-- statistically analyzes map coincidence for significant
difference and outputs a summary table.
Composite-- Creates a map summarizing values from one map that
coincide with the categories of another.
Compute-- Creates a map as the mathematical or statistical
function of two or more maps.
Configure-- Assigns new values characterizing the shape of the area
associated with each category.
Copy-- Creates a
new map by copying an old map.
Correlate-- Identifies correlation among maps and outputs a
principal components summary table.
Cover-- Creates a new map where transparent values of the top
map replace the values on the previous (bottom) map or stack of maps.
Crosstab-- Generates a spatial coincidence table of two maps.
Describe-- Creates a tabular summary of the contents (legend) of a
map.
Drain-- Creates a map indicating the number of steepest paths
(optimal path density) from a set of locations along a surface.
Export-- Generates a data file of map information in a variety of
formats for transfer to other programs.
Import-- Assigns values to cells defined by data files of map
information in a variety of transfer formats.
Import_Table-- Assigns values to cells defined by the columns in a
standard data base file (.dbf).
Interpolate-- Creates a continuous surface from point data.
Intersect-- Creates a map that
assigns new values to pairwise combinations of values on two maps.
Orient-- Creates a map indicating aspect along a continuous
surface.
Profile-- Creates a map indicating the cross-sectional profile
along a continuous surface.
Radiate-- Creates a map indicating areas that are visible from
locations specified on the “viewers map.”
Regress-- Generates a multiple regression equation and statistics
for a stack of maps.
Relate-- Creates a map of similarity for a specified location(s)
on a stack of maps to all other locations within a map area.
Renumber-- Assigns new values to the categories of a map.
Scan-- Creates a map summarizing the values that occur within
the vicinity of each cell.
Size-- Assigns new values according to the size of the area
associated with each map category.
Slice--
Assigns new
values by dividing the range of values on a map into specified intervals
(contouring).
Slope-- Creates a map indicating the slope (1st derivative)
along a continuous surface.
Span-- Creates a map indicating the narrowness within areas
associated with each category of a map.
Spread-- Creates a map indicating the shortest effective distance
from specified cells to all other locations.
Stream-- Creates a map identifying the steepest downhill route
along a surface (optimal path).
Tabulate-- Generates a standard data base file (.dbf) containing
cell values for a set of maps.
Varray— Primitive-level procedure for handling data.
Listing of
Operations by Functional Group
Reclassify Operations— New values are assigned as a function
of the initial value, size, shape, or contiguity of each map category on a map.
Overlay Operations— New values are
assigned as a function of the independent values associated with each map
location or categories on two or more existing maps.
Distance Operations— New values are assigned as a function
of the simple or effective distance, optimal movement, narrowness, or visual
connectivity among map locations.
Neighborhood Operations— New values are assigned as a function
of the independent values within a specified distance and direction around each
map location.
Statistical Operations— New values and summary
tables/statistics/equations are calculated using a variety of descriptive and
predictive statistical procedures.