cgshaperange.pro
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; docformat = 'rst'
;
; NAME:
; cgShapeRange
;
; PURPOSE:
; Determines the X (longitude) and Y (latitude) data range of the entities in a shapefile.
;
;******************************************************************************************;
; ;
; Copyright (c) 2012, by Fanning Software Consulting, Inc. All rights reserved. ;
; ;
; Redistribution and use in source and binary forms, with or without ;
; modification, are permitted provided that the following conditions are met: ;
; ;
; * Redistributions of source code must retain the above copyright ;
; notice, this list of conditions and the following disclaimer. ;
; * Redistributions in binary form must reproduce the above copyright ;
; notice, this list of conditions and the following disclaimer in the ;
; documentation and/or other materials provided with the distribution. ;
; * Neither the name of Fanning Software Consulting, Inc. nor the names of its ;
; contributors may be used to endorse or promote products derived from this ;
; software without specific prior written permission. ;
; ;
; THIS SOFTWARE IS PROVIDED BY FANNING SOFTWARE CONSULTING, INC. ''AS IS'' AND ANY ;
; EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES ;
; OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT ;
; SHALL FANNING SOFTWARE CONSULTING, INC. BE LIABLE FOR ANY DIRECT, INDIRECT, ;
; INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED ;
; TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; ;
; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ;
; ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ;
; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS ;
; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. ;
;******************************************************************************************;
;
;+--------------------------------------------------------------------------
; Determines the X (longitude) and Y (latitude) data range of the entities in a shapefile.
;
; :Categories:
; Utilities, Map Projections
;
; :Author:
; FANNING SOFTWARE CONSULTING::
; David W. Fanning
; 1645 Sheely Drive
; Fort Collins, CO 80526 USA
; Phone: 970-221-0438
; E-mail: david@idlcoyote.com
; Coyote's Guide to IDL Programming: http://www.idlcoyote.com
;
; :Examples:
; shapeBoundary = cgShapeRange('states.shp')
;
; :Returns:
; A four-element array containing the extent of the entity data in the
; shapefile, in the order [xrange[0], yrange[0], xrange[1], yrange[1]].
;
; :Params:
; shapefile: in, optional, type=string
; The name of the shapefile for which you wish to know the extent.
; If not provided, the user will be asked to pick a shapefile.
;
; :Keywords:
; mean: out, optional, type=float
; A two-element float or double array giving the mean or average X value
; and the mean or average Y value of the entities in the shapefile, respectively
; median: out, optional, type=float
; A two-element float or double array giving the median X value
; and the median Y value of the entities in the shapefile, respectively
; xrange: out, optional, type=float
; A two-element float or double array giving the minimum and maximum
; extent of the shapefile entities in the X (longitude) direction, respectively
; yrange: out, optional, type=float
; A two-element float or double array giving the minimum and maximum
; extent of the shapefile entities in the Y (latitude) direction, respectively
;
; :History:
; Modification History::
; Written by David W. Fanning by 29 August 2012.
;
; :Copyright:
; Copyright (c) 2012, Fanning Software Consulting, Inc.
;---------------------------------------------------------------------------
FUNCTION cgShapeRange, shapefile, $
MEAN=mean, $
MEDIAN=median, $
XRANGE=xrange, $
YRANGE=yrange
Compile_Opt idl2
; Return to caller on error.
On_Error, 2
; Need a shapefile?
IF N_Elements(shapefile) EQ 0 THEN BEGIN
shapefile = cgPickfile(Title='Select a SHAPEFILE...', Filter='*.shp')
IF shapefile EQ "" THEN RETURN, FltArr(4)
ENDIF
; Open the shape file and create the shape object.
shapefileObj = Obj_New('IDLffShape', shapefile)
IF Obj_Valid(shapefileObj) EQ 0 THEN $
Message, 'Unable to create shape file object. Returning...'
; Get all the attribute pointers from the file. These are the entities.
entities = Ptr_New(/Allocate_Heap)
*entities = shapefileObj -> GetEntity(/All, /Attributes)
; Get the entity data ranges.
entityMinX = FltArr(N_Elements(*entities))
entityMaxX = FltArr(N_Elements(*entities))
entityMiny = FltArr(N_Elements(*entities))
entityMaxY = FltArr(N_Elements(*entities))
FOR j=0,N_Elements(*entities)-1 DO BEGIN
thisEntity = (*entities)[j]
entityMinX[j] = thisEntity.bounds[0]
entityMaxX[j] = thisEntity.bounds[4]
entityMiny[j] = thisEntity.bounds[1]
entityMaxY[j] = thisEntity.bounds[5]
ENDFOR
xrange = [Min(entityMinX), Max(entityMaxX)]
yrange = [Min(entityMinY), Max(entityMaxY)]
; Need mean values?
IF Arg_Present(mean) THEN BEGIN
xmean = Mean([entityMinX, entityMaxX])
ymean = Mean([entityMinY, entityMaxY])
mean = [xmean, ymean]
ENDIF
; Need median values?
IF Arg_Present(median) THEN BEGIN
xmedian = Median([entityMinX, entityMaxX])
ymedian = Median([entityMinY, entityMaxY])
median = [xmedian, ymedian]
ENDIF
; Clean up.
Obj_Destroy, shapefileObj
Ptr_Free, entities
; Return the extent of the data.
RETURN, [xrange[0], yrange[0], xrange[1], yrange[1]]
END