Using arcpy dictionaries to select attributes from a different layer

Question

I'd like to incorporate the use of dictionaries to access data between tables. So far I have been able to create the dictionaries that I need from my feature class fields. I have one dictionary that lists multiple Property values for one key [(u'1010305', [u'1014414', u'1014395', u'1014381']), (u'1010306', [u'1014396', u'1014415', u'1014432', u'1014414', u'1014395', u'1014382', u'1014381']).... I would like to use the values associated to each key to select rows ("select by attribute") in another table. While I can call the values by key or item in the command window I can't seem to incorporate them into a SelectLayerByAttribute function. This is the code so far :

# Purpose: Create a dictionary of values that combines Recipient Claims to Allocating Claims from the BufferRecipientClaims feature class.
# Usage: No arguments needed.
# Source : Python for ArcGIS, Laura Tateosian, 2015, Springer, Chapter 18 p.349.
import arcpy, numpy
arcpy.env.workspace = "CURRENT"
fc = "RecipientBufferClaims"
# Populate the dictionary,
# accumulate a list of Recipient Claims (Value) for each Allocation Claim (Key) type.
dict = {}
SearchCurs = arcpy.da.SearchCursor("RecipientBufferClaims",["RecClmNum","AllocClmNum"])
for row in SearchCurs:
 Recipient = row[0]
 Allocation = row[1]
 if dict.has_key(Recipient):
 dict[Recipient].append(Allocation)
 else:
 dict[Recipient] = [Allocation]
del SearchCurs

All of which works. I'd like to use something like the following to select rows in a new table using the returned values for the key "1010305" but I'm getting an error message

for k, v in dict.values["1010305"]:
 AllocationVariable = AllocationVariable(v)
 print "the allocation claim numbers are {0} ".format(AllocationVariable)
 arcpy.selectLayerByAttribute(fc,""" "AllocClmNum" = AllocationVariable """)
Runtime error 
Traceback (most recent call last):
 File "<string>", line 1, in <module>
ValueError: too many values to unpack

Edit: I did manage to get this to update another table, unfortunately it did so without filtering the values associated to the key 1010305, but I'm getting closer (code below).

with arcpy.da.UpdateCursor("ActualTbleCopy2SortedAllocationClaims",["AllocClmNum","CorrAllocCreVal"]) as UpdateCurs:
 for row in UpdateCurs:
 for k, v in dict.items():
 RecipientNumber = str(k)
 if RecipientNumber == ("1010305"):
 row[1] = 9999
 UpdateCurs.updateRow(row)

• gene: Where are the k v values in your for loop ?
• Frederic: As I understand it the k and v values refer to my Key and Value elements in my dictionary : "AllocClmNum","CorrAllocCreVal" in the first set of code.
• jon_two: If you get the 'too many values to unpack' error, you need to enclose your k,v variables in brackets so they are treated as a tuple: for (k, v) in ...
• jon_two: Also, 'dict' is a reserved word, so is not a good variable name. Try calling it myDict or something else.
• Frederic: @jon_two. Thanks for your suggestions. I'll change my 'dict' variable and keep your solution for the 'too many values to unpack' in mind as I progress. Excellent points.

Answer 1

a few things:

1. when you store your multiple values for each key make sure it a tuple and not a list

2. After you correctly stored your key value(tuple) pairs in your dictionary. Try calling the dictionary like this

   for k,v in dict.items():
    if k = "1010305":
    qry = "AllocClmNum IN {}".format(v)
    arcpy.selectLayerByAttribute(fc, qry)
   

EDIT: saving you v values to a variable

for k,v in dict.items():
 if k = "1010305":
 values = tuple(v)
 qry = "AllocClmNum IN {}".format(values)
 arcpy.selectLayerByAttribute(fc, qry)

to index you would just do something like this:

ex: print values[1]
 print values[3] etc...

• Frederic: Thank you, that seems like the solution I am looking for. But I'm not clear on how I change my multiple values for each keys into a tuple rather than a list. Something like : tupleValues = (row[0],row[1])?
• ziggy: You just want the values stored in the tuple - not the key
• ziggy: dict[Recipient] = (Allocation)
• ziggy: what does your dictionary look like when you print it out? maybe i am not understanding it correctly
• Frederic: Thanks again. Using your code suggestion above I get the following printed dictionary result :'AllocClmNum IN [u'1014414', u'1014395', u'1014381'] which is exactly what I want it to return : the values that are associated to the key value. Can these values now be accessed by index? I need to use these values to select rows from another table based on each of these values and then run another calculation.