Python-Creating Short Label Field Based on Another Field

[DonalCasey1]

I have a field in the attribute table of ArcMap that contains either the value 'Freehold' or 'Leasehold'. I have another field that contains a unique ID of each polygon. I would like to create a third field called 'Short Label' that I can use to label everything from F1..F60  and L1...L60 based on the Tenure in my table. I would then use this as my label field and I would insert a table into the layout as a lookup.

Would anybody be able to help me write a python script to create the short label field based on the Tenure type?

Thanks

Tenure	Unique ID	Short Label
Freehold	EGL2266995	F1
Leasehold	NGL4459756	L1

[DanPatterson_Retired]

Is that an actual portion of the table or a replica.

What is the association between the Freeholder/leaseholder and the unique ID field.

If you have a Tenure column as shown, getting the F or L is easy.. slice it  

python parser, !Tenure![0] will get the first letter... it is the numbers to concatenate with then is the key.

[DonalCasey1]

Dan_Patterson That is just a replica of the table, I put in examples of what I need the short label to be.

There is no association between the freehold/leaseholder and the unique ID field. I simple want the person reading the map in the end to know that if a label has the prefix 'F' that it is a freehold and 'L' is a leasehold. If I slice the tenure column like demonstrated above is it possible to then suffix with numbers? Thanks

[DanPatterson_Retired]

There is always a way... this is via a demonstration.  If it is what you want, it can be simplified and used in a code block in the field calculator.  Let me know if there are any other variants.  I used 'F' and 'N' to represent your cases because I felt like it....

a = ['F', 'F', 'N', 'N', 'F', 'N', 'F', 'N', 'F', 'F']
f0 = 0
n0 = 0
def hdr(a):
    global f0
    global n0
    frst = a[0]
    if frst == 'F':
        rtrn = "F{}".format(f0)
        f0 += 1
    else:
        rtrn = "N{}".format(n0)
        n0 += 1
    return rtrn

for i in a:
    print(hdr(i))‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Which returns

# commentary added after the print run
F0  # F found first
F1  # then again
N0  # N found first
N1  # then again
F2  # back to F
N2  # ooopsie another N
F3  # and so on
N3
F4
F5‍‍‍‍‍‍‍‍‍‍‍

[JoshuaBixby]

Using Dan's example as an example, Python's itertools module has an increment counter if you don't want to use global.

from itertools import count

a = ['F', 'F', 'N', 'N', 'F', 'N', 'F', 'N', 'F', 'F']
fcount = count()
ncount = count()
def hdr(a):
    frst = a[0]
    if frst == 'F':
        rtrn = "F{}".format(fcount.next())
    else:
        rtrn = "N{}".format(ncount.next())
    return rtrn‍‍‍‍‍‍‍‍‍‍‍‍