A tool for generating heatmaps from housing price data
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Bopriskartan is a tool for generating heatmaps, visualizing the price development of housing. It takes a csv file as input and generates a png file as output. This png can then be used as a custom layer on for instance, google maps.

A simple scraper script is included which fetches sold prices from Booli:s Api and prints the to stdout.

Getting started

In order to use the tool, Go must be installed on your machine.

Clone the repository to $GOPATH/src.


The project uses dep as dependency management tool. In order to build the project, go/dep must first be installed.

$> go get -u github.com/golang/dep/cmd/dep 

The project can then be built by the included Makefile.

$> make

or it can be compiled directly with go build from the src directory.

$> go get
$> go build heatmap.go main.go -o heatmap

Creating a heatmap

In order to create a heatmap we need one or more data files containing prices for sold housing objects and a configuration file which tells both the scraper and the heatmap generator which area the prices are covering.

Configuration file

The configuration must be written in yaml format and contain the following fields:

name: stockholm
heatmap_width: 1000
heatmap_height: 1000
heatmap_step: 5000
min_price_limit: 20000
max_price_limit: 120000
lat_lo: 59.205634
lng_lo: 17.846684
lat_hi: 59.439306
lng_hi: 18.266219
lat_center: 59.324818
lng_center: 18.072342
zoom: 13
Name Description
name Title of the html page
heatmap_width The width of the generated png
heatmap_height The height of the generated png
heatmap_step The step in price between max_price_limit and min_price_limit, determines how many color buckets will be generated in between
min_price_limit First color bucket
max_price_limit Last color bucket
lat_lo, lat_hi Latitude values
lng_lo, lng_hi Longtitude values
lat_center, lng_center The center point on the generated map
zoom The zoom level of the generated map

lat_lo, lng_lo, lat_hi and lng_hi should together create a rectangular box of a geographic area. (lat_hi, lng_hi) are the northeast corner and (lat_lo, lng_lo) are south west corner.

Scraping data

A small python (3) script is included in the repo which loads data from the Booli Api and prints the data to stdout in correct format.

$>./scraper.py -h
usage: scraper.py [-h] -c CONFIG_PATH -f 2017-01-01 -t 2017-01-07
                  [-o {villa, lägenhet, gård, tomt-mark,fritidshus, parhus,radhus,kedjehus}]

Booli API scraper for sold objects

optional arguments:
  -h, --help            show this help message and exit
                        Path to config file
  -f 2017-01-01, --from_date 2017-01-01
                        Date to query objects from
  -t 2017-01-07, --to_date 2017-01-07
                        Date to query objects to
  -o {villa, lägenhet, gård, tomt-mark,fritidshus, parhus,radhus,kedjehus}, --object_type {villa, lägenhet, gård, tomt-mark,fritidshus, parhus,radhus,kedjehus}
                        Type of object to query (optional)

In order to use the script, you need to have a booli API account. The username and key must then be set as environment variables.

$> export BOOLI_USERNAME={your username}
$> export BOOLI_KEY={your key}

Then the scraper can be used to pull price data from the API.

$> ./scraper.py -c {path/to/config.yml} -f 2017-01-01 -t 2017-01-31 -o 'lägenhet' > data.csv

The data file has the following structure:

$> head data.csv

Generating a heatmap from the data file

The heatmaps are generated with the heatmap_gen binary.

$> ./heatmap -h
Usage of ./heatmap:
  -b	Prints bucket list to output
  -c string
        Path to config file (default "config.yml")
  -d string
        Path to input data
  -o string
        Path to output (default "/.")

When you have a csv file containing price data, a heatmap can be generated:

$> cat data.csv | heatmap_gen -c {path/to/config.yml} -o heatmap.png

Also, the color buckets can be generated to a file as a json object.

$> ./heatmap_gen -c {path/to/config.yml} -o color_buckets.json -b

Creating the map

Now when we have the heatmap image we can add it as a custom layer ontop of a map. A python (3) scripts is included which makes use of a html template in jinja format. The generated html file will be placed in the same directory as the configuration file.

$> ./template_gen.py -h
usage: template_gen.py [-h] -c CONFIG_PATH [-t TEMPLATE_PATH] [-b BUCKET_PATH]
                      [-f FILES]

Generates a google maps page with the heatmaps as custom overlays. The program
takes a list of paths to the heatmaps as input to stdin or they can be
provided with the -f flag

optional arguments:
  -h, --help            show this help message and exit
                        Path to config file
                        Path to template file
                        Path to bucket file
  -f FILES, --files FILES
                        (optional) Comma seperated list of pathsto heatmap

Given a configuration file, a heatmap, a bucket.json and a template (which is included) a html file can be generated.

$> find . -name "*.png" | ./template_gen -c /{path/to/config.yml} -t template.html.j2 -b color_buckets.json