Multi batch spatial joins

[2Quiker]

I have over 20 layers that I need to spatially join, doing separate arcpy.SpatialJoin_analysis for each one would be time consuming.  fc1 is the layer I want to multi batch the other layers in the database to.

I have tried the following but it only spatially joins the first layer in the database. Is it possible to do a multi batch spatial joins? I am going about it the wrong way?

import arcpy, os  
from arcpy import env
from datetime import datetime as d
startTime = d.now()

arcpy.env.workspace = r"C:\Temp\Default2.gdb"  
fc1 = r"C:\Temp\Default2.gdb\Parcels"

arcpy.env.overwriteOutput = True
fcs = arcpy.ListFeatureClasses() #gets the feature classes
for fc in fcs:
    print(fc)
    arcpy.SpatialJoin_analysis(fc1,fc, "SP_Test", "JOIN_ONE_TO_ONE", "KEEP_ALL", "", "INTERSECT", "", "")
print ('(Elapsed time: ' + str(d.now() - startTime)[:-3] + ')')

fc1 

[BlakeTerhune]

Is your goal to have one feature class with everything smashed into it (as many spatial joins) or to have separate feature classes, each spatial joined to only Parcels?

[2Quiker]

To have one feature class with certain fields and rename some fields. I can keep certain fields with the following but I need to change some fields names and just the whole fieldmappings gives me a headache.

fieldmappings = arcpy.FieldMappings()

    # Add all fields from inputs.
    fieldmappings.addTable(fc1)
    fieldmappings.addTable(fc)

    # Name fields you want. Could get these names programmatically too.
    keepers = ["Field1", "Field2", "Field3", "Field4","Field5", "Field6"] # etc.

    # Remove all output fields you don't want.
    for field in fieldmappings.fields:
        if field.name not in keepers:
            fieldmappings.removeFieldMap(fieldmappings.findFieldMapIndex(field.name))

I need to be able to rename  "Field1", "Field2", "Field3", "Field4","Field5", "Field6" to something else, "AFieldA", "BFieldB", "CFieldC", "DFieldD","EFieldE", "FFieldF". No specifically these names but to something else. I also need to use a merge rule and join delimiter to one layer in the database.

[Anonymous User]

Here is the code that handles the spatial joining process:

def fieldmapping(targetFc, joinFc, keepFields):
    """
    Support function create a field map between two featureclasses
    """
    fldMap = arcpy.FieldMappings()
    # Creating field maps for the two files
    fldMap.addTable(targetFc)
    fldMap.addTable(joinFc)

    # Adds the fields from the targetFC to the list of fields that you want to keep
    keepFields.extend(i.name for i in arcpy.ListFields(targetFc))

    # Removing unwanted fields
    for field in fldMap.fields:
        if field.name not in keepFields or field.name in ['TARGET_FID', 'Join_Count']:
            fldMap.removeFieldMap(fldMap.findFieldMapIndex(field.name))

    return fldMap
        
# ----------------- 
def joinsubdivision():
    # List of fields that you want to keep from the input featureclass 
    subd = ['sub_code', 'blk_tr_no', 'lot_no', 'sub_name', 'plat_year', 'plat_month']
    # helper function to map the target featureclass to the input featureclasses fields that you want to keep.
    subdMap = fieldmapping(updatedAddress, subdivision, subd)
    lyrInMem = arcpy.SpatialJoin_analysis(inLayer, subdivision, os.path.join(in_memory, 'subdiv'), 'JOIN_ONE_TO_ONE', 'KEEP_ALL', subdMap, 'INTERSECT')
     # If needed, alter field names (alternative to having to create a specific field map for the field)
    altfields(lyrInMem, [('blk_tr_no', 'blk_tr')])

Hope this gives you an idea to get started and if you have any questions please feel free to ask.

[2Quiker]

Where are you defining 'altfields', 'updateAddress' and 'subdivisions'?

[Anonymous User]

Yes, that could help.

altfields is a helper method that takes a list of tuples and runs them through arcpy.AlterField_management() to rename them:

def altfields(inLayer, flds):
    """
    Support function to alter fields
    """
    for f in flds:
        arcpy.AlterField_management(inLayer, f[0], f[1], f[1])

its use is something like:

altfields(yourlayer, [('DMSLat', 'latitude'), ('panel', 'firm_panel')])

'updateAddress' is the target featureclass that you want to join the other featureclasses to.

'subdivision' is the feature class that you want to join to the target featureclass.

Both of these are just variables pointing to featureclasses, which you'll change to match yours.

I see ESRI's example has changed and has improved some over the one tree example, but there is a lot of additional things happening in the example that is distracting from being able to clearly see how to make a field map.

If you want to rename the fields in the fieldmapping, you can do so by doing this:

fldMap = arcpy.FieldMappings()
... # map like fields and exclude fields you dont want 

#-----------------------
# create specific mapped fields:
specificfldmap = arcpy.FieldMap() # create FieldMap object

# add the target featureclass and its field name that you want to map.
specificfldmap.addInputField(targetfc, 'targetfcfldname') 

# add the joining featureclass and its field name that you want to map.
specificfldmap.addInputField(joinfc, 'joinfcfldname') 

# get the outputfield object
specfldobj = specificfldmap.outputField 

# set the desired outputfield name
specfldobj.name = 'newoutputfieldname'

# replace the outputfield object with the modifed version
specificfldmap.outputField = specfldmapobj 

# add your fieldmap to your fieldMappings object
fldMap.addFieldMap(specificfldmap)

# proceed with using the fldMap

You can iterate over a list of tuples for this part if you know the fieldnames and what you want to be mapped to in the target featureclass.

[Lyle-GIS-Analyst]

I came to this thread (four years later woo) looking for a solution to do my own batch spatial join, where I could get the count of points within polygons with just the one polygon layer, but about 11 different point layers. This code currently makes a copy for each spatial join, but I think that can be easily worked around- I just don't want this to break right now and I spent 6 hours figuring this out so bear with me, I was also doing this within ArcGIS Pro's Python window, so I didn't need to set the workspace. I sincerely hope this helps others figure this out faster than I did:

import time #I used a function at the end to wait 3 seconds just because I find that
#when Python in Pro works a bit too fast it can mess up, especially with spatial joins. This isn't really necessary.
#first create a list with each layer you want to join to your main layer
pointfc = ["pointlayer1", #0 - I use notes after lists I iterate through to help me remember which is which, especially if I add some later that point to separate spots in either list. This example looks nicer than some real uses for it.
            "pointlayer2", #1
            "pointlayer3", #2
            "pointlayer4", #3
            "pointlayer5", #4
            "pointlayer6", #5
            "pointlayer7", #6
            "pointlayer8", #7
            "pointlayer9", #8
            "pointlayer10", #9
            "pointlayer11"] #10
#second, I made a list of field names, this is because I hate ESRI's field mapping function
fieldlist = ["fieldname1", #0 -> 0
             "fieldname2", #1 -> 1
             "fieldname3", #2 -> 2
             "fieldname4", #3 -> 3
             "fieldname5", #4 -> 4
             "fieldname6", #5 -> 5
             "fieldname7", #6 -> 6
             "fieldname8", #7 -> 7
             "fieldname9", #8 -> 8
             "fieldname10", #9 -> 9
             "fieldname11"] #10 ->10
#Next, I made a string list that I could alter later with the field mapping from the
#layer I am joining to, I left it as it was just to show how I made it but yours should not be the exact same
fieldmapping = ['id "ID" true true false 4 Long 0 0,First,#,polygonfc,id,-1,-1;',
   'sectorid "SectorID" true true false 50 Text 0 0,First,#,polygonfc,sectorid,0,49;',
   'publicstatus "PublicStatus" true true false 4 Long 0 0,First,#,polygonfc,publicstatus,-1,-1;',
   'market "market" true true false 10 Text 0 0,First,#,polygonfc,market,0,9;',
   'chassis "chassis" true true false 25 Text 0 0,First,#,polygonfc,chassis,0,24;']

#this is where we iterate through the points to join them one at a time
for i in range(len(pointfc)):
   print(fieldlist[i]) #not necessary, just used to help identify which step I was on
#here we append the next field mapping that is needed, this one is putting in the
#desired field name and getting a count of the "ticket" field because that's what I
#wanted to count, your field will look different but the idea is to get the right
#field name for the initial joining.
   fieldmapping.append(fieldlist[i]+' "'+fieldlist[i]+'"'+' true true false 12 Double 0 0,Count,#,i,ticket,0,11;')
#I recognize the "i,ticket" part there maybe is not being used correctly, but this still
#worked right so I really don't know what to say
#then we make the holy grail of field mapping without using ESRI's function
#fmj is Field Mapping Join, and this just puts the list back together into
#that one ugly long string for the join code to look at normally
   fmj = str(''.join(fieldmapping))
   print(fmj) #I used this to make sure I was looking at things right, it isn't necessary
   if i == 0: #because I was going through each one separately and making a new layer each time, the first time had to be slightly different.
        arcpy.analysis.SpatialJoin(
            target_features="polygonfc",
            join_features=pointfc[i],
            out_feature_class=r"C:/blah/blah/path/blah/polygonfc"+str(i), #used str(i) here just to differentiate the step and notate which point set I was on
            join_operation="JOIN_ONE_TO_ONE",
            join_type="KEEP_ALL",
            field_mapping=fmj,#here goes that field mapping variable, looks so much nicer this way
            match_option="INTERSECT",
            search_radius=None,
            distance_field_name="",
            match_fields=None
            )
   else: #this is the actual, normal operation, it targets the previous join to go off of.
        arcpy.analysis.SpatialJoin(
            target_features="polygonfc"+str(i-1), #grabs previous join to build off of
            join_features=pointfc[i],
            out_feature_class=r"C:/blah/blah/path/blah/polygonfc"+str(i),
            join_operation="JOIN_ONE_TO_ONE",
            join_type="KEEP_ALL",
            field_mapping=fmj,
            match_option="INTERSECT",
            search_radius=None,
            distance_field_name="",
            match_fields=None
            )
   fieldmapping[i+5] = (fieldlist[i]+' "'+fieldlist[i]+'"'+' true true false 12 Double 0 0,First,#,polygonfc,'+fieldlist[i]+',0,11;') #this part is very important
#the i+5 is based on the number of attributes present in the feature, which grows by
#one each time this iterates through since we are keeping the count of each previous join.
#We mainly have to make sure the end part changes from "Count,#,i,ticket,0,11;" to "First,#,polygonfc,'+fieldlist[i]+',0,11;"
#so that we don't accidentally set all fields in the joins to the last join done.
#This part tripped me up quite a bit until I figured that out.
   time.sleep(3) #here is that 3 second sleep, you may not need it, I may not need it, but I am more comfy with it there
#after that it will loop back up and grab the next join until there are no more joins.
#this code isn't perfect, I know there is likely a better way to not make a number of features equal to the joins done
#but it works and it is a start, and I wanted to provide that to others who may be able to work with it better.