Conditional Numbering points/polygons in ArcGIS 2010

PhoukhongPhongsa

In Excel, I can do:

In cell B2 =IF(A2=A1, B1+1,1)

Data in A1:A20

A     B

1     1

1     =IF(A2=A1, B1+1,1)

1

2

2

2

2

3

3

...

How can I do in ArcGIS Attribute Table using field calculator?

I use the AutoIncreament() ... but it work according to the OBJECT_ID and that is not CONDITIONAL...

Your help is very appreciate!

Khong

PhoukhongPhongsa

I tried it but not working.

The auto increment sorted by OBJECT_ID is okay but no condition!

Pre-Logic Script Code:

rec=0

def autoIncrement():

global rec

pStart = 1 #adjust start value, if req'd

pInterval = 2 #adjust interval value, if req'd

if (rec == 0):

rec = pStart

else:

rec = rec + pInterval

return rec

Expression:

autoIncrement()