#!F-adobe-helvetica-medium-r-normal--18*
#!N 
#!CNavyBlue #!N  #!Rexavgc AverageCell Module 
Example--Average the Data Values of All Neighbors #!N #!EC #!N #!N 
The AverageCell module computes, for each cell, the average of the 
data values of that cell and all its neighbors. #!N Note: 
This module works only on data that is cell-centered (i.e., connection-dependent) 
and has connections of type "quads." #!N #!N #!N The AverageCell 
module takes one input:  #!F-adobe-times-bold-r-normal--18*   input #!EF , of type  #!F-adobe-times-bold-r-normal--18*   
field #!EF , which has no default value. The module has 
one output:  #!F-adobe-times-bold-r-normal--18*   output #!EF , of type  #!F-adobe-times-bold-r-normal--18*   field #!EF 
. #!N #!N  #!F-adobe-times-bold-r-normal--18*   (1) START THE MODULE BUILDER #!EF with 
the command: __________________________________ #!CForestGreen #!N #!N  #!F-adobe-courier-bold-r-normal--18*   #!N dx -builder #!EF 
#!N #!N #!EC #!N #!N The Module Builder dialog box appears. 
Note that the dialog box carries no information, since no module 
has been specified. (For a simple example of creating a module 
with the Module Builder, see  #!Ltmodbld,dxall1006 h Using the Module Builder: A Quick Walk Through  #!EL  ). #!N #!N  #!F-adobe-times-bold-r-normal--18*   (2) 
SELECT ___________  #!F-adobe-times-bold-r-normal--18*   OPEN #!EF #!EF from the _______________________  #!F-adobe-times-bold-r-normal--18*   File 
#!EF pull-down menu. An  #!F-adobe-times-bold-r-normal--18*   Open a Module Builder file... #!EF 
dialog box appears. #!N #!N  #!F-adobe-times-bold-r-normal--18*   (3) READ IN #!EF /opt/local/dx/samples/program_guide/averagecell.mb 
as follows: __________________ #!N #!I0 #!N  #!F-adobe-times-medium-r-normal--18*   #!N #!N #!I30 #!N 
o Type the full path name in the  #!F-adobe-times-bold-r-normal--18*   Filter #!EF 
field of the dialog box. #!N #!I30 #!N o Click on 
(in sequence): #!N #!I0 #!N  #!F-adobe-times-medium-r-normal--18*   #!N #!N #!I30 #!N - 
the  #!F-adobe-times-bold-r-normal--18*   Filter #!EF button #!N #!I30 #!N - the name 
of the file in the  #!F-adobe-times-bold-r-normal--18*   Files #!EF field #!N #!I30 
#!N - the  #!F-adobe-times-bold-r-normal--18*   OK #!EF button. #!N #!I0 #!N #!EF 
#!N Information describing the inputs and output of the module (extracted 
from the averagecell.mb file) appears in the Module Builder dialog box. 
#!N #!I0 #!N #!EF #!N #!N #!N  #!F-adobe-times-bold-r-normal--18*   (4) SAVE THE 
.MB FILE #!EF to a writable directory (use ___________________________  #!F-adobe-times-bold-r-normal--18*   Save 
As... #!EF in the  #!F-adobe-times-bold-r-normal--18*   File #!EF pull-down menu). #!N #!N 
 #!F-adobe-times-bold-r-normal--18*   (5) SELECT #!EF ________________  #!F-adobe-times-bold-r-normal--18*   Create All #!EF from the 
 #!F-adobe-times-bold-r-normal--18*   Build #!EF pull-down menu of the dialog box. This option 
creates three files for the module: averagecell.c, averagecell.mdf, and averagecell.make, #!N 
#!N  #!F-adobe-times-bold-r-normal--18*   (6) IMPLEMENT THE AVERAGECELL FUNCTION #!EF . ____________________________________________ #!N 
#!N Use an editor to add the following lines after "User's 
code goes here" in the averagecell.c file: #!CForestGreen #!N #!N  #!F-adobe-courier-bold-r-normal--18*   
#!N int *itemcounts = NULL, i, neighbor; #!N #!N /* make 
scratch space to hold the number of items added for each 
element */ #!N itemcounts = DXAllocate(input_knt*sizeof(int)); #!N if (!itemcounts) #!N goto 
error; #!N #!N /* #!N * first initialize the output data 
component to zero, and itemcounts to #!N * zero. #!N */ 
#!N for (i=0; i<input_knt; i++) { #!N output_data[i] = 0; #!N 
itemcounts[i]=0; #!N } #!EF #!N #!N #!EC #!CForestGreen #!N #!N  #!F-adobe-courier-bold-r-normal--18*   
#!N /* for each data value, add that value to the 
appropriate items in the #!N * output data array. Also increment 
itemcounts for those cells. #!N */ #!N for (i=0; i<input_knt; i++) 
{ #!N /* first do itself */ #!N output_data[i]+=input_data[i]; #!N itemcounts[i]++; 
#!N #!N /* now do neighbors in fastest-varying dimension */ #!N 
neighbor = i-1; #!N if (neighbor >= 0 && ((i % 
(c_counts[1]-1)) != 0)) { #!N output_data[neighbor]+=input_data[i]; #!N itemcounts[neighbor]++; #!N } #!EF 
#!N #!N #!EC #!CForestGreen #!N #!N  #!F-adobe-courier-bold-r-normal--18*   #!N neighbor = i+1; 
#!N if (neighbor < input_knt &&(((i+1)%(c_counts[1]-1)) != 0)) { #!N output_data[neighbor]+=input_data[i]; 
#!N itemcounts[neighbor]++; #!N } #!N #!N /* now do neighbors in 
the slowest-varying dimension */ #!N neighbor = i - (c_counts[1]-1); #!N 
if (neighbor >= 0) { #!N output_data[neighbor]+=input_data[i]; #!N itemcounts[neighbor]++; #!N } 
#!N neighbor = i + (c_counts[1]-1); #!N if (neighbor < input_knt) 
{ #!N output_data[neighbor]+=input_data[i]; #!N itemcounts[neighbor]++; #!N } #!N } #!EF #!N 
#!N #!EC #!CForestGreen #!N #!N  #!F-adobe-courier-bold-r-normal--18*   #!N /* now divide by 
the number of items added for that cell */ #!N for 
(i=0; i< input_knt; i++) #!N output_data[i] = output_data[i]/itemcounts[i]; #!N #!N DXFree((Pointer)itemcounts); 
#!N return OK; #!N error: #!N DXFree((Pointer)itemcounts); #!N return ERROR; #!N 
} #!EF #!N #!N #!EC #!N #!N The file /opt/local/dx/samples/program_guide/averagecell.c contains 
a completed version of this program. #!N #!N  #!F-adobe-times-bold-r-normal--18*   (7) TO 
CREATE A VERSION OF DATA EXPLORER THAT INCLUDES #!EF the AverageCell 
module, enter the command: ____________________________________________________________ #!CForestGreen #!N #!N  #!F-adobe-courier-bold-r-normal--18*   #!N make 
-f averagecell.make dxexec #!EF #!N #!N #!EC #!N #!N (You have 
now created an executable that contains the AverageCell module.) #!N #!N 
 #!F-adobe-times-bold-r-normal--18*   (8) TO INVOKE THIS VERSION, ENTER: #!EF _________________________________________ #!CForestGreen #!N 
#!N  #!F-adobe-courier-bold-r-normal--18*   #!N dx -edit -mdf ./averagecell.mdf -exec ./dxexec #!EF #!N 
#!N #!EC #!N #!N This command starts Data Explorer (the averagecell.mdf 
file tells the graphical user interface about AverageCell and its inputs 
and outputs). The executable dxexec invoked here is the one created 
in Step 6. #!N #!N  #!F-adobe-times-bold-r-normal--18*   (9) WITH THIS VERSION OF 
DATA EXPLORER #!EF you can now run any visual program that 
uses the AverageCell module. ____________________________________________ One such program is /opt/local/dx/samples/program_guide/averagecell.net #!N 
#!N #!N  #!F-adobe-times-medium-i-normal--18*   Next Topic #!EF #!N #!N  #!Limptd,dxall1036 h Importing Data  #!EL  #!N  #!F-adobe-times-medium-i-normal--18*   
#!N 
