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A Tcl interface to read Shapefiles

tclshp is an extension of Tcl/Tk that provides the Tcl script writer some ability to read shapefiles. Its core is a set of C wrappers that read the files using Frank Warmerdam's shapelib and make the results available to Tcl procedures.

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Resources:

Functions

shp s -open input_file

opens shapefile, returns the name of a command used for subsequent operations

$s info

returns a list containing {shape_type record_count}

$s bounds rowid

returns a list containing {Xmin Ymin Zmin Mmin Xmax Ymax Zmax Mmax} for the whole shapefile or, if rowid is specified, the bounds of that specific shape.

$s coords rowid

returns coordinates for the given shape.

Since shapes can be composed of multiple parts, this function always returns a list of lists; one sublist for each part in the shape. It is the sublists that contain the coordinate values. So the coordinates of a simple shape will be returned as a list containing the list of coordinates. For shapes that are known to be two-dimensional, only the X and Y coordinates are included; if the shape might have Z coordinates or measures, all four coordinate values are given.

$s forget

closes the shapefile

Installation

1. You'll need Tcl/Tk installed on your system in order to make use of this software. You can download Tcl/Tk from ActiveState, the company that currently provides an excellent free distribution: http://www.activestate.com/Products/ActiveTcl/
2. If you want to modify or compile the source code, you will need shapelib (URL above). Install that in a directory adjacent to tclshp and run the tcl script setup.tcl included with tclshp.

Technical contact:

    Peter N. Schweitzer
    Mail Stop 954, National Center
    U.S. Geological Survey
    Reston, VA 20192

    Tel: (703) 648-6533
    FAX: (703) 648-6252
    Email: pschweitzer@usgs.gov