topic Re: Update Cursor Issue: Multiple nested If Elif Else in Python Questions

Update Cursor Issue: Multiple nested If Elif Else

KristaMerry — Fri, 10 Dec 2021 22:28:51 GMT

I am trying to work through an Update cursor issue. I have a forest stands shapefile with the following fields: Age, Historical Community (Hist_Comm), Pine Basal Area (PINE_BA), Fire Return Interval (FIRE_FRQ), Time Since Last Fire (LAST_YR), and then a Class (ECC). The goal is to use the AGE, Hist_Comm, FIRE_FRQ, and LAST_YR fields along with several user inputs to assign an ECC value.

This is how it would work:

If the Historical Community field (Hist_Comm) is greater than 3:

and If the Age (Min_Age1) is greater than 80:

and if the Pine Basal Area (Min_PineBA1) is greater than or equal to 40 or Pine Basal Area (Max_PineBA1) is less

than or equal to 60:

and if the Fire Frequency (Max_FI1) is less than 3 and the Time Since Last Fire (Max_FY1) is less than 3:

then ECC = 1

or elif the Fire Frequency (Min_FI1) is greater than or equal to 3 but less than or equal to 6 (Max_FI1) and the Time

Since Last Fire (Max_FY1) is less than or equal to 6:

then ECC = 3

It should search through the attribute table selecting the rows from the fields Hist_Comm, AGE, PINE_BA, FIRE_FRQ, and LAST_YR that fit the above criteria and assign then assign a value to the ECC field.

I think (stress think) I am having an issue with the user inputs working within multiple levels of nested if statements.

The script has been added to a toolbox. Each input variable Data Type is defined as a string. Each input variable will be an integer value.

Here's the code (also attached):

# Import arcpy module
import arcpy

# Set Workspace
arcpy.env.workspace = 'C:\\ECC_Test\\Output'

# Set Input Parameters
Min_Age1 = arcpy.GetParameterAsText(0) 
Min_PineBA1 = arcpy.GetParameterAsText(1) 
Max_PineBA1 = arcpy.GetParameterAsText(2)
Min_FI1 = arcpy.GetParameterAsText(3)
Max_FI1 = arcpy.GetParameterAsText(4)
Max_FY1 = arcpy.GetParameterAsText(5)

# Define Variables
fc = "C://ECC_Test//Output//Stands_2_t.shp"

#Update Cursor
with arcpy.da.UpdateCursor(fc, ["Hist_Comm", "FIRE_FRQ", "LAST_YR", "AGE", "PINE_BA", "ECC"]) as cursor:
    for row in cursor:
       if (row[0] >= 3) and (Min_Age1 >= 80) and (row[3] >= 80):
         if (Min_PineBA1 >= 40) and (Max_PineBA1 <= 60) and(row[4] >= 40) and (row[4] <= 60):
             if (Max_FI1 < 3) and (row[1] < 3) and (Max_FY1 < 3) and (row[2] < 3): 
                row[5] = 1 
             elif (Min_FI1 >= 3) and (row[1] >= 3) and (Max_FI1 <= 6) and (row[1] >= 3) and (Max_FY1 <= 6) and (row[2] <= 6): 
                row[5] = 3
             else:
                row[5] = 4
          cursor.updateRow(row)

 
 del cursor, row‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Update Cursor Issue: Multiple nested If Elif Else

DanPatterson_Retired — Fri, 10 Dec 2021 22:28:55 GMT

before my head bursts....

what are you supposed to do if this line fails? there is no where to go

if (row[0] >= 3) and (Min_Age1 >= 80) and (row[3] >= 80):
‍

PS I took the liberty of formatting your code... follow the 3 dots on the editor bar, select More, then Syntax highlighting and paste your code and select Python

Re: Update Cursor Issue: Multiple nested If Elif Else

NeilAyres — Wed, 07 Sep 2016 06:34:47 GMT

Sorry, but what do you mean by this :

"Each input variable Data Type is defined as a string. Each input variable will be an integer value." ??

Are the inputs strings or integers?

Re: Update Cursor Issue: Multiple nested If Elif Else

KristaMerry — Fri, 10 Dec 2021 22:28:57 GMT

Dan,

Thank you for reformatting the code. In my haste i didn't see the Python formatting.

I also forgot to include the final "else" in the code. So if the data doesn't meet those criteria it is assigned a zero.

#Update Cursor

with arcpy.da.UpdateCursor(fc, ["Hist_Comm", "FIRE_FRQ", "LAST_YR", "AGE", "PINE_BA", "ECC"]) as cursor:
    for row in cursor:
        if (row[0] >= 3) and (Min_Age1 >= 80) and (row[3] >= 80):
            if (Min_PineBA1 >= 40) and (Max_PineBA1 <= 60) and(row[4] >= 40) and (row[4] <= 60):
                if (Max_FI1 < 3) and (row[1] < 3) and (Max_FY1 < 3) and (row[2] < 3):                           
                    row[5] = 1                       
                elif (Min_FI1 >= 3) and (row[1] >= 3) and (Max_FI1 <= 6) and (row[1] >= 3) and (Max_FY1 <= 6) and (row[2] <= 6): 
                    row[5] = 3
                else:
                    row[5] = 4
            cursor.updateRow(row)       
        else:
            row[5] = 0
        
            
    del cursor, row‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Update Cursor Issue: Multiple nested If Elif Else

KristaMerry — Wed, 07 Sep 2016 13:02:51 GMT

Neil,

Your question helped me with one issue and pointed out my boneheaded mistake. They are integers and are now defined as Long not String.

Thanks!

Krista

Re: Update Cursor Issue: Multiple nested If Elif Else

KristaMerry — Wed, 07 Sep 2016 13:36:19 GMT

With the String to Long fix, I am only getting the ECC classes of 0 and 4 being assigned. In querying the attribute table I can see that there are data that should be classified as class 3 but are classified as 4.

I am sure there is something pretty straight forward I am missing. I am new to using Cursors so bare with me.

Re: Update Cursor Issue: Multiple nested If Elif Else

XanderBakker — Wed, 07 Sep 2016 14:48:36 GMT

The "else" will never trigger an update of the row, with the code posted.

Re: Update Cursor Issue: Multiple nested If Elif Else

XanderBakker — Fri, 10 Dec 2021 22:29:00 GMT

You have to revise the logic of obtaining the ECC classes. See the example below. I have no idea where the values for in_Age1, Min_PineBA1, Max_PineBA1, Max_FY1, Min_FI1, Max_FI1 come from.

I created a function to get the ECC class, but I see that you are checking twice on the same line for the fire frequency (see line 9). Furthermore, is last_yr really a value that low? You may want to include some print statements to see what happens. It has nothing to do with the update cursor.

def getECC(hist_comm, fire_frq, last_yr, age, pine_ba,
           Min_Age1, Min_PineBA1, Max_PineBA1, Max_FY1, Min_FI1, Max_FI1):
    ecc = -1
    try:
        if (hist_comm >= 3) and (Min_Age1 >= 80) and (age >= 80):
            if (Min_PineBA1 >= 40) and (Max_PineBA1 <= 60) and(pine_ba >= 40) and (pine_ba <= 60):
                if (Max_FI1 < 3) and (fire_frq < 3) and (Max_FY1 < 3) and (last_yr < 3):
                    ecc = 1
                elif (Min_FI1 >= 3) and (fire_frq >= 3) and (Max_FI1 <= 6) and (fire_frq >= 3) and (Max_FY1 <= 6) and (last_yr <= 6):
                    ecc = 3
                else:
                    ecc = 4
        else:
            ecc = 0
    except Exception as e:
        print(e)
        ecc = -1
    finally:
        return ecc

# where do these variables come from?
# Min_Age1, Min_PineBA1, Max_PineBA1, Max_FY1, Min_FI1, Max_FI1

#Update Cursor
with arcpy.da.UpdateCursor(fc, ["Hist_Comm", "FIRE_FRQ", "LAST_YR", "AGE", "PINE_BA", "ECC"]) as cursor:
    for row in cursor:
        ecc = getECC(row[0], row[1], row[2],row[3], row[4],
                     Min_Age1, Min_PineBA1, Max_PineBA1, Max_FY1, Min_FI1, Max_FI1)
        row[5] = ecc
        cursor.updateRow(row)


del cursor, row‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Update Cursor Issue: Multiple nested If Elif Else

DarrenWiens2 — Fri, 10 Dec 2021 22:29:03 GMT

I believe your original explanation can be re-written like below (every 'if' should have a corresponding 'else').

However, I think the larger problem is that you probably want to compare the row values to the input values. So, rather than comparing the user input value (Min_Age1) to 80, you want to see if the current row age value is greater than the user input value: row[3] > Min_Age1.


# Import arcpy module
import arcpy

# Set Workspace
arcpy.env.workspace = 'C:\\ECC_Test\\Output'

# Set Input Parameters
Min_Age1 = arcpy.GetParameterAsText(0) 
Min_PineBA1 = arcpy.GetParameterAsText(1) 
Max_PineBA1 = arcpy.GetParameterAsText(2)
Min_FI1 = arcpy.GetParameterAsText(3)
Max_FI1 = arcpy.GetParameterAsText(4)
Max_FY1 = arcpy.GetParameterAsText(5)

# Define Variables
fc = "C://ECC_Test//Output//Stands_2_t.shp"

#Update Cursor
with arcpy.da.UpdateCursor(fc, ["Hist_Comm", "FIRE_FRQ", "LAST_YR", "AGE", "PINE_BA", "ECC"]) as cursor:
    for row in cursor:
        if (row[0] >= 3) and (Min_Age1 >= 80) and ((Min_PineBA1 >= 40) or (Max_PineBA1 <= 60)):
            if (Max_FI1 < 3) and ((Max_FY1 < 3)):
                row[5] = 1
            elif (Min_FI1 >= 3) and (Max_FI1 <= 6) and (Max_FY1 <= 6):
                row[5] = 3
            else:
                row[5] = 222
                print 'Did not pass second test'
        else:
            row[5] = 111
            print 'Did not pass first test'
        cursor.updateRow(row)‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍