Using dictionary in field calculator

SSISC_FieldCrew

I am working with the field calculator in ArcPro. I have created a dictionary where the Key is an existing value in a field and the value is the one I would like to replace the existing value with. Below is a portion of my dictionary.

plant_dictionary = {
    "ABUT THE": "Velvet leaf",
    "ACRO REP": "Russian knapweed",
    "AEGI CYL": "Jointed goatgrass",
    "AEGO POD": "Goutweed / bishop's weed",
    "AILA ALT": "Tree of heaven",
    "ALHA MAU": "Camel thorn",
    "ALLI PET": "Garlic mustard"
}

 then I have this bit of code where INV_SP_PLA is the field whose data I am trying to replace.

for r in plant_dictionary:
    if !INV_SP_PLA! in r:
        !INV_SP_PLA!.replace(r, plant_dictionary[r])
    else:
        pass

ArcPro does not like my dictionary for some reason and I am unsure of what to put in the Expression portion of the field calculator.  

Any ideas why this might not be working?

DWynne

@SSISC_FieldCrew, to start, I would recommend updating a new field, at least until you're sure you have the logic the way you want. 

To follow along with what Dan showed, I tried the following:

 

Expression:

plant(!INV_SP_PLA!)

 

Code Block:

plant_dictionary = {
    "ABUT THE": "Velvet leaf",
    "ACRO REP": "Russian knapweed",
    "AEGI CYL": "Jointed goatgrass",
    "AEGO POD": "Goutweed / bishop's weed",
    "AILA ALT": "Tree of heaven",
    "ALHA MAU": "Camel thorn",
    "ALLI PET": "Garlic mustard"
}

def plant(val):
    """Demo"""
    if val in plant_dictionary.keys():
        new_val = plant_dictionary[val]
        return new_val
    else:
        return val
    

 

Given the below table, the updated values are shown in the `new` field:

I included an `else` condition to return the original value if it's not in the dictionary. Like Joshua mentioned, variations in the original field values would result in some values not being updated.