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add time constraint to near tool

QiuhuaMa

Hi,

I am working on my dissertation right now and need to use Arcgis to calculate the distance from the nearest fire to each house.

Since fire is polygon and house is point, I just use near tool to calculate distance from the nearest fire to the house. However the fires I am interested in is the fire that burned within the past 7 years before the sale of the homes. So I need to exclude all fires that burned after the sale date of the home, and all fires that burned greater than seven years before the sale of the home.

Is there anyway to add a time constraint to near tool using python?

thanks,

chelsea

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Accepted answers

XanderBakker

OK, I had some fun with the data and this is what I obtained as result (houses drawn on distance to nearest fire):

Preparation:

I projected the Fire polygons to the same spatial reference as the houses

Change in the code below:

paths to input data on lines 7 and 8

Code:

import arcpy
from datetime import datetime, date, timedelta
from dateutil.relativedelta import relativedelta

def main():
    # input fc's
    fc_house = r"C:\Forum\DistFireHouse\shp\housesaledata.shp"
    fc_fire = r"C:\Forum\DistFireHouse\shp\firehistory_NAD_fips3002_feet.shp"

    # input field
    fld_date_sale = "ma_date_dt"

    # output fields
    fld_dist = "Dist2Fire"
    fld_fire_oid = "FireOID"

    # add fields
    addField(fc_house, fld_dist, "DOUBLE")
    addField(fc_house, fld_fire_oid, "LONG")

    # loop through houses
    cnt = 0
    flds = ("SHAPE@", fld_date_sale, fld_dist, fld_fire_oid)
    with arcpy.da.UpdateCursor(fc_house, flds) as curs:
        for row in curs:
            cnt += 1
            if cnt % 25 == 0:
                print "Processing house: {0}".format(cnt)
            pnt = row[0]
            date_sale = row[1]
            row[2], row[3] = getNearestFire(fc_fire, pnt, date_sale)
            curs.updateRow(row)


def addField(fc, fldname, fldtype):
    if len(arcpy.ListFields(fc, wild_card=fldname)) == 0:
        arcpy.AddField_management(fc, fldname, fldtype)

def getNearestFire(fc, pnt, date_sale):
    # input fields
    fld_year = "FIRE_YEAR"
    fld_month = "FIRE_MONTH"
    fld_day = "FIRE_DAY"

    # defaults
    min_dist = 999999
    oid_fire = -1

    flds = ("SHAPE@", "OID@", fld_year, fld_month, fld_day)
    with arcpy.da.SearchCursor(fc, flds) as curs:
        for row in curs:
            polygon = row[0]
            oid = row[1]
            year = int(row[2])
            try:
                month = int(row[3])
            except:
                month = 6
            try:
                day = int(row[4])
            except:
                day = 15

            if chkDate(date_sale, year, month, day):
                dist = pnt.distanceTo(polygon)
                if dist < min_dist:
                    min_dist = dist
                    oid_fire = oid

    return min_dist, oid_fire

def chkDate(date_sale, year_fire, month_fire, day_fire):
    date_fire = datetime(year=year_fire, month=month_fire, day=day_fire)
    date_2monthsbefore_sale = date_sale + relativedelta(months=-2)
    year_sale = date_sale.year
    test = (year_fire >= year_sale - 7) and (date_fire < date_2monthsbefore_sale)
##    if test:
##        print "date_sale: {0}".format(date_sale)
##        print "date_fire: {0}".format(date_fire)
##        print "date_2monthsbefore_sale: {0}".format(date_2monthsbefore_sale)
##        print "year_sale: {0}".format(year_sale)
##        print "{0}  <  {1}  <  {2}".format(year_sale-7, date_fire, date_2monthsbefore_sale)
    return test

if __name__ == '__main__':
    main()

All comments

JamesCrandall

Can you just apply a definition query on the fire layer that meets your requirements then run your tool? Or do you have a specific python script that needs modified to accomplish this?

XanderBakker

I assume that the sale of each house can have a different date, right? In that case the definition query on the fires per house would be different. In that case you don't really need to use the Near tool, but you could use the geometries to determine the distance. Do you have a maximum search distance defined?

This would require a loop through the houses, determine the date of sale, define the where clause based on the date to use in the search cursor for the fire polygons, calculate the distance, keep track of the shortest distance and store this as a result probably as an attribute for the current house.

If that is what you are looking for, and maybe if you can share a small part of your data, we can create a script to get that result.

QiuhuaMa

Xander, you are right! Each house has a different sale date. I didn't

define the maximum search distance.

What you said is exactly what I want to do! I tried to do this manually but

it took so much time!

I attached part of my house sale data and fire history data. Parcelid is

parcel id for each house. Ma_date_dt is sale date of each house.

For each fire, I have fire_day, fire_month and fire_year!

If a house is sold on 07/15/2013, I would like to find the nearest fire to

this house that burned between 2006 and 05/2013.

if a house is sold on 05/02/2011, I would like to find the nearest fire to

the house that burned between 2004 to 03/2011.

I would like to restrict the beginning time to year but the end time

to month/year.

thanks so much,

Chelsea

datatest_update.zip

QiuhuaMa

the end time of fire need to be 2 month earlier than house sale time since

most sale process took longer than 2 month.

XanderBakker

OK, I had some fun with the data and this is what I obtained as result (houses drawn on distance to nearest fire):

Preparation:

I projected the Fire polygons to the same spatial reference as the houses

Change in the code below:

paths to input data on lines 7 and 8

Code:

import arcpy
from datetime import datetime, date, timedelta
from dateutil.relativedelta import relativedelta

def main():
    # input fc's
    fc_house = r"C:\Forum\DistFireHouse\shp\housesaledata.shp"
    fc_fire = r"C:\Forum\DistFireHouse\shp\firehistory_NAD_fips3002_feet.shp"

    # input field
    fld_date_sale = "ma_date_dt"

    # output fields
    fld_dist = "Dist2Fire"
    fld_fire_oid = "FireOID"

    # add fields
    addField(fc_house, fld_dist, "DOUBLE")
    addField(fc_house, fld_fire_oid, "LONG")

    # loop through houses
    cnt = 0
    flds = ("SHAPE@", fld_date_sale, fld_dist, fld_fire_oid)
    with arcpy.da.UpdateCursor(fc_house, flds) as curs:
        for row in curs:
            cnt += 1
            if cnt % 25 == 0:
                print "Processing house: {0}".format(cnt)
            pnt = row[0]
            date_sale = row[1]
            row[2], row[3] = getNearestFire(fc_fire, pnt, date_sale)
            curs.updateRow(row)


def addField(fc, fldname, fldtype):
    if len(arcpy.ListFields(fc, wild_card=fldname)) == 0:
        arcpy.AddField_management(fc, fldname, fldtype)

def getNearestFire(fc, pnt, date_sale):
    # input fields
    fld_year = "FIRE_YEAR"
    fld_month = "FIRE_MONTH"
    fld_day = "FIRE_DAY"

    # defaults
    min_dist = 999999
    oid_fire = -1

    flds = ("SHAPE@", "OID@", fld_year, fld_month, fld_day)
    with arcpy.da.SearchCursor(fc, flds) as curs:
        for row in curs:
            polygon = row[0]
            oid = row[1]
            year = int(row[2])
            try:
                month = int(row[3])
            except:
                month = 6
            try:
                day = int(row[4])
            except:
                day = 15

            if chkDate(date_sale, year, month, day):
                dist = pnt.distanceTo(polygon)
                if dist < min_dist:
                    min_dist = dist
                    oid_fire = oid

    return min_dist, oid_fire

def chkDate(date_sale, year_fire, month_fire, day_fire):
    date_fire = datetime(year=year_fire, month=month_fire, day=day_fire)
    date_2monthsbefore_sale = date_sale + relativedelta(months=-2)
    year_sale = date_sale.year
    test = (year_fire >= year_sale - 7) and (date_fire < date_2monthsbefore_sale)
##    if test:
##        print "date_sale: {0}".format(date_sale)
##        print "date_fire: {0}".format(date_fire)
##        print "date_2monthsbefore_sale: {0}".format(date_2monthsbefore_sale)
##        print "year_sale: {0}".format(year_sale)
##        print "{0}  <  {1}  <  {2}".format(year_sale-7, date_fire, date_2monthsbefore_sale)
    return test

if __name__ == '__main__':
    main()

XanderBakker

Since it may be a little difficult to verify the result I threw in another piece of code to aid the verification process:

These are lines that connect each house with the nearest fire and add the date info to the lines for verification.

FireDate is the date of the fire
ma_date_dt is the date when the house was sold
YrSaleMn7 is the year of sale minus 7 years
SaleMin2m is the date two months before the house was sold
The FireOID can be used to join additional data from the fire polygons to the lines (use the FID of the fire polygons)
The parcelid provides the link to the houses.

What you need to do is change these lines in the code below:

reference the input shapefiles on line 10 and 11
define the output shapefile on line 23

Run the code below:

import arcpy
import os
from datetime import datetime, date, timedelta
from dateutil.relativedelta import relativedelta

def main():
    arcpy.env.overwriteOutput = True

    # input fc's
    fc_house = r"C:\Forum\DistFireHouse\shp\housesaledata.shp"
    fc_fire = r"C:\Forum\DistFireHouse\shp\firehistory_NAD_fips3002_feet.shp"


    # input field house
    fld_fire_oid = "FireOID"
    fld_parcel_id = "parcelid"
    fld_date_sale = "ma_date_dt"

    # input fields fires
    fld_oid_fire = arcpy.Describe(fc_fire).OIDFieldName

    # output fc
    fc_out = r"C:\Forum\DistFireHouse\shp\lines01.shp"

    # output fields (parcelid, double)
    fld_sale_min7 = "YrSaleMin7"
    fld_sale_2month = "SaleMin2m"
    fld_fire_date = "FireDate"
    fld_dist = "Dist2Fire"

    # create empty output fc
    sr = arcpy.Describe(fc_house).spatialReference
    shp_folder, shp_name = os.path.split(fc_out)
    arcpy.CreateFeatureclass_management(shp_folder, shp_name, "POLYLINE", spatial_reference=sr)

    # add output fields
    addField(fc_out, fld_parcel_id, "DOUBLE")
    addField(fc_out, fld_fire_oid, "LONG")
    addField(fc_out, fld_date_sale, "DATE")
    addField(fc_out, fld_fire_date, "DATE")
    addField(fc_out, fld_sale_min7, "INTEGER")
    addField(fc_out, fld_sale_2month, "DATE")
    addField(fc_out, fld_dist, "DOUBLE")

    # loop through houses
    cnt = 0
    flds_out = ("SHAPE@", fld_parcel_id, fld_fire_oid, fld_date_sale,
                fld_fire_date, fld_sale_min7, fld_sale_2month, fld_dist)
    flds_house = ("SHAPE@", fld_parcel_id, fld_date_sale, fld_fire_oid)
    with arcpy.da.InsertCursor(fc_out, flds_out) as curs_out:
        with arcpy.da.SearchCursor(fc_house, flds_house) as curs_in:
            for row_in in curs_in:
                cnt += 1
                if cnt % 25 == 0:
                    print "Processing connection: {0}".format(cnt)
                pnt1 = row_in[0]
                parcel_id = row_in[1]
                date_sale = row_in[2]
                fire_oid = row_in[3]

                # get fire details
                pnt2, date_fire = getDetailsFirePolygon(fc_fire, fld_oid_fire, fire_oid, pnt1)

                # create the lines
                line = arcpy.Polyline(arcpy.Array([pnt1.firstPoint, pnt2.firstPoint]), sr)

                date_2monthsbefore_sale = date_sale + relativedelta(months=-2)
                year_salemin7 = date_sale.year - 7

                row_out = (line, parcel_id, fire_oid, date_sale, date_fire,
                           year_salemin7, date_2monthsbefore_sale, line.length, )
                curs_out.insertRow(row_out)


def getDetailsFirePolygon(fc_fire, fld_oid_fire, fire_oid, pnt):
    fld_year = "FIRE_YEAR"
    fld_month = "FIRE_MONTH"
    fld_day = "FIRE_DAY"

    where = "{0} = {1}".format(arcpy.AddFieldDelimiters(fc_fire, fld_oid_fire), fire_oid)
    row = arcpy.da.SearchCursor(fc_fire, ("SHAPE@", fld_year, fld_month, fld_day), where_clause=where).next()
    polygon = row[0]
    year_fire = int(row[1])
    try:
        month_fire = int(row[2])
    except:
        month_fire = 6
    try:
        day_fire = int(row[3])
    except:
        day_fire = 15

    date_fire = datetime(year=year_fire, month=month_fire, day=day_fire)

    polyline = polygon.boundary()
    pnt2 = polyline.queryPointAndDistance(pnt, False)[0]

    del row
    return pnt2, date_fire

def addField(fc, fldname, fldtype):
    if len(arcpy.ListFields(fc, wild_card=fldname)) == 0:
        arcpy.AddField_management(fc, fldname, fldtype)

if __name__ == '__main__':
    main()

Add the result to ArcMap and define two relates on the lines featureclass:

one linking the lines to the houses using the parcelid fields
the other linking the lines to the fires using the Fireoid and FID fields

QiuhuaMa

thanks so much, Xander!

I am a Econ student and don't have any programming skills. I tried read

your script but can only understand a few.

I will run your code and compare it to results that I got earlier to see

whether they are consistent.

Except for fire history in the past 7 years, I also would like to do fire

history in the past 10, 15 and 20 years.

It seems to me that I only need to change the code in the following 2 lines:

def chkDate(date_sale, year_fire, month_fire, day_fire):

date_fire = datetime(year=year_fire, month=month_fire, day=day_fire)

date_2monthsbefore_sale = date_sale + relativedelta(months=-2)

year_sale = date_sale.year

test = (year_fire >= year_sale - 7) and (date_fire <

date_2monthsbefore_sale)

if test:
print "date_sale: print "date_fire:

".format(date_sale) ".format(date_fire)

print "date_2monthsbefore_sale: print "year_sale: ".format(date_2monthsbefore_sale) ".format(year_sale)

print " < < ".format(year_sale-7, date_fire,

date_2monthsbefore_sale)

return test

if __name__ == '__main__':

main()

Am I right? Are there any other changes that I need to make?

thanks,

Chelsea

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