How to assign a unique Value for cells

5683
6
10-25-2011 08:49 AM
ABDALLAMOHAMED
Occasional Contributor
Hi..I wanted to assign a unique value (number) for each cell in the grid..I just wonder if any one can help me ..For my knowledge ArcMap 10 has no such tool, and I guess the only way to do it is through python programming..That is my thought, I may be wrong, don't know..Appreciate if some one can help me out..
Thanks a lot...
0 Kudos
6 Replies
DanPatterson_Retired
MVP Esteemed Contributor
Below provides some food for thought, please consult the appropriate help topics for other options.

>>> import numpy as np
>>> unique = np.arange(100)
>>> unique = unique.reshape(10,10)
>>> unique
array([[ 0,  1,  2,  3,  4,  5,  6,  7,  8,  9],
       [10, 11, 12, 13, 14, 15, 16, 17, 18, 19],
       [20, 21, 22, 23, 24, 25, 26, 27, 28, 29],
       [30, 31, 32, 33, 34, 35, 36, 37, 38, 39],
       [40, 41, 42, 43, 44, 45, 46, 47, 48, 49],
       [50, 51, 52, 53, 54, 55, 56, 57, 58, 59],
       [60, 61, 62, 63, 64, 65, 66, 67, 68, 69],
       [70, 71, 72, 73, 74, 75, 76, 77, 78, 79],
       [80, 81, 82, 83, 84, 85, 86, 87, 88, 89],
       [90, 91, 92, 93, 94, 95, 96, 97, 98, 99]])
>>> import arcpy
>>> out_raster = arcpy.NumPyArrayToRaster(unique)
>>> out_raster.save("c:/temp/testRaster")
>>>
0 Kudos
ABDALLAMOHAMED
Occasional Contributor
Thanks Dan..Let me give it a try and see, I never used Python before..??
0 Kudos
markdenil
Regular Contributor II
A non-Python way is to create a fishnet exactly the same as the grid you want: same extents, same cell size.
Build polygons from the fishnet lines
The polygons will all have unique feature ids.
convert the field of little square polygons to a raster with cells the same size as your little squares, using the (unique) feature ids as the value.
0 Kudos
LukeWebb
Occasional Contributor III
Hi,

Similar to the fishnet...this requires the correct tool (spatial analyst?) licenses but is very straight forward.

Use Raster to point tool - creates a point theme with a value field from the raster (These values I assume you do not require)

Then calculate a unique ID field in this dataset using field calculater --> FID / ObjectID

Finally, Point to Raster tool - select your uniqueID values field instead of the original value field.

Done.



Then
0 Kudos
ABDALLAMOHAMED
Occasional Contributor
Thanks all of you for your contributions..Appreciated..
0 Kudos
LT1
by
New Contributor
Hi..I wanted to assign a unique value (number) for each cell in the grid..I just wonder if any one can help me ..For my knowledge ArcMap 10 has no such tool, and I guess the only way to do it is through python programming..That is my thought, I may be wrong, don't know..Appreciate if some one can help me out..
Thanks a lot...



Hi mykotti,

I'm looking for simple examples of using numpy for GIS and this seems like a good one -- except I don't really can't guess (or conjure) a reason for creating a raster with a unique value for each cell.  Could you explain?  Thanks.  -- LT
0 Kudos