Lernia

lernia logo
lernia logo

Lernia is a machine learning library for autmomated learning on geo data and time series.

library description

Content:

modules descriptions

modules are divided into main blocks:

time series

computing

geographical

basics

learning

Data structure

Every single time series is represented as a

shapeLib

redF = t_s.reduceFeature(X)
redF.interpMissing()
redF.fit(how="poly")
redF.smooth(width=3,steps=7)
dayN = redF.replaceOffChi(sact['id_clust'],threshold=0.03,dayL=sact['day'])
dayN[dayN['count']>30].to_csv(baseDir + "raw/tank/poi_anomaly_"+i+".csv",index=False)
XL[i] = redF.getMatrix()

replace missing

We homogenize the data converting the time series into matrices to make sure we have data for each our of the day. We than replace the missing values interpolating:

replace_nan replace missing values via interpolation

smoothing

In order to compensate the effects of time shifting (can counts double within two hours?) we apply a interpolation and smoothing on time series:

re../f/f_smoothing to the raw reference data we apply: 1) polynomial interpolation 2) smoothing

chi square distribution

Some locations are particularly volatile and to monitor the fluctuations we calculate the χ2 and control that the p-value is compatible with the complete time series. We substitute the outliers with an average day for that location and we list the problematic locations.

re../f/f_volatility Distribution of p-value from χ2 for the reference data

We than replace the outliers:

replace_volatility outliers are replaced with the location mean day, left to right

feature importance

We studied the statistical properties of a time series collecting the most important features to determine data quality. stat prop most important statistical properties of time series

We calculate the feature importance on model performances based on statistical properties of time series of reference data. importance statistical properties we obtain a feature importance ranking based on 4 different classification models

We try to predict model performances based on statistical properties of input data but the accuracy is low which means, as expected, that the quality of input data is not sufficient to explain the inefficiency in the prediction. stat prop traininig training on statistical properties of input data vs model performances

We now extend our prediction based on pure reference data and location information feature importance feature importance based on location information and input data

Knowing the location information we can predict the performace within 80% of the cases. confusion matrix confusion matrix on performance prediction based on location information

reduce features

We select the most relevant weather features over a selection of 40. weather feature correlation between weather features

Other weather related parameters have an influence on the mismatch. weather_correlation weather has an influence on the deviation: di../f/f

We use the enriched data to t

Regression

All the skews we have shown are used to train predictors and regressors to adjust counts: model_score ROC of different models on training data

Thanks to the different corrections we can adjust our counts to get closer to reference data. regressor_curves corrected activities after regressor

We have structure the analysis in the following way: year structure structure of the calculation for the yearly delivery

We can than adjust most of the counts to meet the project KPIs

kpi_dist distribution of the KPIs ρ and δ

Shape clustering

We want to recognize the type of user clustering different patterns:

user patterns different patterns for kind of user

We calculate characteristic features by interpolating the time series. We distinguish between a continous time series where we can calculate the overall trends via the class train_shapeLib.py

time series time series of a location and the daily average where we can understand the typical daily activity.

daily average daily average of a location Many different parameters are useful to improve the match between mobile and customer data, parameters as position of the peak, convexity of the curve, multiday trends help to understand which cells and filters are capturing the activity of motorway stoppers.

shape clustering clustering curves (average per cluster is the thicker line) depending on different values of: intercept, slope, convexity and trend

Unfortunately no trivial combination of parametes can provide a single filter for a good matching with customer data. We need then to train a model to find the best parameter set for cells and filter selection.

Feature selection

We need to find a minimal parameter set for good model performances and spot a subset of features to use for the training. We realize that some features are strongly correlated and we remove highly correlated features

correlation matrix correlation between features

name description variance
trend1 linear trend 5.98
trend2 quadratic trend 4.20
sum overall sum 1.92
max maximum value 1.47
std standard deviation 1.32
slope slope x1 1.11
type location facility 1.05
conv convexity x2 0.69
tech technology (2,3,4G) 0.69
interc intercept x0 0.60
median daily hour peak 0.34

High variance can signify a good distribution across score or a too volatile variable to learn from.

We select five features which have larger variance to increase training cases.

selected features final selection of features

Scoring

We use the class train_shapeLib.py to calculate the score between users data and customer data. We calculate the first score, cor, as the Pearson’s r correlation:
$$ r = \frac{cov(X,Y)}{\sigma_x \sigma_y} $$
This parameter helps us to select the curves which will sum up closely to the reference curve.

scoring explanation the superposition of many curves with similar correlation or many curves with heigh regression weights leads to a good agreeement with the reference curve The second parameter, the regression reg, is the weight, w, given by a ridge regression
$$ \underset{w}{min\,} {{|| X w - y||_2}^2 + \alpha {||w||_2}^2} $$
where α is the complexity parameter.

The third and last score is the absolute difference, abs, between the total sum of cells and reference data:
$$ \frac{|\Sigma_c - \Sigma_r|}{\Sigma_r} $$
per location

libKeras

deep learning autoencoder

We build an autoencoder which is a model that learns how to create an encoding from a set of training images. In this way we can calculate the deviation of a single image (hourly values in a week 7x24 pixels) to the prediction of the model.

week_image sample set of training images, hourly counts per week

In this way we can list the problematic locations and use the same model to morph measured data into reference data.

We train a deep learning model on images with convolution: tensorboard sketch of the phases of learning

We than test how the images turn into themselves after the prediction of the autoencoder.

raw_vs_predicted comparison between input and predicted images

We can than state that 88% of locations are not well predictable by the model within 0.6 correlation. autoencoder_performance distribution of correlation for autoencoder performances: correlation on daily values

implementation

Results generation

Applying both predictor and regressor and we generate: result no order resulting activities per location

We then sort the results depending on a χ2 probability and discard results with an high p_value result order activities sorted by p-value

To summarize we generate the results applying the following scheme: filter structure application of the predictor and regressor

The detailed structure of the files and scripts is summarized in this node-red flow charts: flow chart flow chart of the project

We have structure the analysis in the following way: year structure structure of the calculation for the yearly delivery