DreamCity – Build your own German city


Bring your fictive German city name and get latitude and longitude of it. clustering


With this project I had 2 intensions:

  • Find relations in names of German locations, founding date and the cultures / nations there. For instance I tried to find differences in the naming of locations in the south of the German republic where the former 3 states Großherzogtum BadenKönigreich Württemberg and Königreich Bayern were located. After various clusterings of different parts of the data and predictions, I definitely found clusters there.
  • Back in the days, I was also interested in establishing a small web site, where you can create your village / city / town at a place given by DreamCity. Something like social networks with virtual locations and place for your self realization.

Anyway, now I don’t have the time to a) complete the research here and b) deploy the small funny game. So, the time was right to publish some parts of this work.

How it works

Data from 12.240 largest German cities / towns / locations were used. These locations were annotated with latitude and longitude. Below I listed the steps from data to model:

  1. Location name was divied into n-grams (where n = 3) [1]
  2. Each distinct n-gram (e.g. ‘Ber’ in Berlin) occupies a dimension in the feature vector (dictionary approach)
  3. The feature vector has a size of 5810 dimensions (distinct 3-grams of 12k locations)
  4. Each location is then represented with a 5810 dimensional vector containing {0,1}s like (0,0,0,0,0,1,….,0,1,0,0)
  5. The regressor learns to map this 5810 dimensional vector to the corresponding (lat,lng) pair of the location
  6. The regressor was configured like this: 100 hidden neurons, adam solver[2], adaptive learning rate, 900k iterations with logistic activation function [3]

After the training the results are:

For a sum of 67145.162 kilometers drift (deviation from the correct (lat, lng) pair) over 12237 samples the regressor achieves a mean error per location of: 5.49 kilometers.

Play around

If you want to play around with this code, the following notes could be interesting for you.

Execute dream city regressor

Just start the following script followed by the city name you want from regressor.

> python start_regressor.py Müllerstadt
lat: 50.4615841198 lng: 8.53205433763

Evaluate the regressor on your own

For this the script below can be used on the current regressor using the current n-gram model as feature transformator.

> python eval_regressor.py
sum of all drifts = 67145.1620699
number of samples = 12237
mean drift kilometers = 5.48706072321 km

Train a new regressor

This is also possible. The data set for the training can be found in data/locations.csv. If you want to retrain just with other configurations, change them in train_regressor.py and just re-run it. You can also exchange the data set with your locations and start the training again.

> python train_regressor.py

What else

If you have any ideas or improvements let me know. For further questions on this publication just drop me a message on twitter @AlexanderBresk.


[1] Neuron food on n-grams (https://en.wikipedia.org/wiki/N-gram)

[2] Diederik P. Kingma, Jimmy Ba. Adam: A Method for Stochastic Optimization (https://arxiv.org/abs/1412.6980)

[3] What is the role of activation function in neural nets? (https://www.quora.com/What-is-the-role-of-the-activation-function-in-a-neural-network)

Leave a Reply

Your email address will not be published. Required fields are marked *