Re: Newbie: basic array questions
Re: Newbie: basic array questions
- Subject: Re: Newbie: basic array questions
- From: zauhar <email@hidden>
- Date: Mon, 28 Apr 2003 15:12:39 -0400
On Monday, April 28, 2003, at 02:47 PM, Philip D Riggs wrote:
1. I have a set of points, each with an ID, x-coord, y-coord, and a
time
point. How can I set up a mutable array of this type and access each
item
and any of their 4 attributes?
You create a class to define objects of this type:
myObject.h
@interface myObject : NSObject
{
double x, y, t ;
int ID ;
}
// Accessor methods
- (double) X ;
- (double) Y:
etc.
- (void) setX: (double)x Y:(double)y T:(double)t ID:(int)index ;
etc.
2. I have a 2-dimensional grid of cells, each with a relative location
on a
grid and an idividual value. In C this was implemented as a
two-dimensional
array (cell [x] [y]) with the value being stored at that x-y location.
How
can I set up a 2-D array in Obj-C?
You would need an NSArray (or NSMutableArray), and each element of the
array would be another NSArray. To make a 100 X 100 array of myObject
instances:
NSMutableArray *myArray = [ [ NSMutableArray alloc ]
initWithCapacity:100 ] ;
for( i = 0 ; i < 100 ; ++i )
{
[ myArray addObject: [ [ NSMutableArray alloc ] initWithCapacity:100
] ] ;
for( j = 0 ; j < 100 ; ++j )
{
[ [ myArray objectAtIndex:i ] addObject:[ [ myObject alloc ] init ]
] ;
}
}
To initialize the values of element (i,j):
[ [ [ myArray objectAtIndex:i ] objectAtIndex:j ] setX:0.35 Y:-0.5
T:10.5 ID:10 ] ;
Or something like that...
Randy
P.S. None of the above has been checked, debugged, etc.
In each case, how would I implement this in Obj-C? What is the most
efficient way of accessing them if there are anywhere from 1 to 15,000
items
in each?
Thank you for any responses!
-----------------------------------------------------------------------
-----
----
Philip D. Riggs
GIS Specialist / Laboratory Manager
Environmental Health Advanced Systems Laboratory
Colorado State University
Fort Collins, Colorado
http://ehasl.cvmbs.colostate.edu/
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Randy J. Zauhar, PhD
Assoc. Prof. of Biochemistry
Director, Graduate Program in Bioinformatics
Dept. of Chemistry & Biochemistry
University of the Sciences in Philadelphia
600 S. 43rd Street
Philadelphia, PA 19104
Phone: (215)596-8691
FAX: (215)596-8543
E-mail: email@hidden
Web:
http://tonga.usip.edu/zauhar
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