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How To: Reclassify a floating point grid

Summary

Note:
This article pertains to ArcGIS versions 8.x only. Later versions of ArcGIS may contain different functionality, as well as different names and locations for menus, commands and geoprocessing tools.

ArcInfo GRID's RECLASS function only reclassifies integer grids. Use this trick to reclassify your floating point grid. Be aware that some values may be rounded.

Procedure

  1. Decide how many decimal places to keep. Take the number of decimal places to keep and add one. Then raise ten to that power. The result is your multiplier. Use this formula to find the needed multiplier.
<multiplier> = 10^(# of decimals to keep + 1)

For example, this dataset must retain 2 decimal places:

1000 = 10^3 = 10^(2 + 1)  
  1. Multiply the grid by the multiplier.
Grid: SETWINDOW dem
Grid: SETCELL dem
Grid: demx1000 = dem * 1000  
  1. Reclassify the grid based on your reclass table.
Grid: demrcls = RECLASS(demx1000,demx1000.rmp)  
Note:
 You will need to modify values in the reclass table to reflect the new grid values.  
  1. Divide the grid by the multiplier to regain the floating point values.
Code:
Grid: demfinal = demrcls / 1000