arcpy.da.SearchCursor storing data in a list with a query

Question

I am currently working with a database that hold street names, x and y coordinates and many more fields. I would like, through a search cursor, to store the x,y coordinates in a separate list for every street name (unique string).

For example, I have 23 entries under Washington street (with 23 x and 23 y coordinates). I would like to find a way to create a list named washington and store the coordinates in that list, and do that for every single street in my database inside a for loop.

For now, all I got is 1 big list with all the data :

spatialjoin = arcpy.env.workspace + '\SpatialJoin_test.shp'

coord=[]

cursor=arcpy.da.SearchCursor(spatialjoin, ['Road_Name','X','Y'])

for row in cursor:

    print(row)

    coord.append(row)

Answer 1

Use collections.defaultdict(list) to store your data:

import arcpy, collections

fc = r'C:\data.gdb\somefeatureclass' #Or shapefile
fields = ['Road_Name','X','Y']

d = collections.defaultdict(list)

with arcpy.da.SearchCursor(fc,fields) as cursor:
    for roadname,x,y in cursor:
        d[roadname].append([x,y])

Key will be roadname and values will be a list of lists of coordinate pairs. For example if you do:

d['Washington street']

you will get:

[[1,2],[1,4],...]

and the 21 remaining coordinate pairs.

Your next step will perhaps be to iterate over keys and values, see this question: Iterating over key and value of defaultdict dictionaries