Sorting feature class to calculate sequential ID field using ArcGIS Field Calculator?

Try using Sort (Data Management) followed by Calculate Field (Data Management) using the auto-increment example on the Calculate Field examples help page.

If you need to sort the data and update it in-place (no intermediate dataset), then I think you would have to use an UpdateCursor which can also sort by a field.

I used ModelBuilder and I did a field sort followed by calculate field using the sort code below and it worked great.

Previously, I had tried these two steps outside of ModelBuilder and it failed.

Expression:

autoIncrement()

Expression Type: PYTHON_9.3

Code Block:

rec=0
def autoIncrement():
    global rec
    pStart = 1 #adjust start value, if req'd 
    pInterval = 1 #adjust interval value, if req'd
    if (rec == 0): 
        rec = pStart 
    else: 
        rec = rec + pInterval 
    return rec