Snippet for concatenating parsed fields without extra spaces

snippet-concat.py

# concatenate parsed address fields without extra spaces
import arcpy
featureClass = "c:\\myfakepath\\data.gdb\\fc"

# create an expression to find records where the STREETNO field is not blank
# this indicates an address to be concatenated
expression = "STREETNO IS NOT NULL"

# create a list of the fields to be concatenated
# (the last field in the list is the field to be concatenated in to)
fields = ["STREETNO","STREETDIR","STREETNAME","STREETSUF","STREETUNIT","STREETADDR"]

# create an update cursor limited to the fields in the fields list, and by the expression
try:
    with arcpy.da.UpdateCursor(featureClass,fields,expression) as cursor:
        for row in cursor:
            if not row[1]:                                      ## if streetdir is null
                exp = "{0} {1}".format(str(row[0]),row[2])      ## streetno + streetname
            else:                                               ## streetdir is not null
                exp = "{0} {1} {2}".format(row[0],row[1],row[2])## streetno + streetdir + streetname
            if row[3]:                                          ## if streetsuf is not null
                exp += " {0}".format(row[3])                    ## add streetsuf to exp
            if row[4]:                                          ## if streetunit is not null
                exp += " {0}".format(row[4])                    ## add streetunit to exp
            row[5] = exp                                        ## set streetaddr field = exp
            cursor.updateRow(row)
except Exception as e:
    error = "Failed: concat fields\n {0} {1}".format(arcpy.GetMessages(), str(e))
    print(error)