Archives of #Py

Overfitting with a Decision Tree

Below is a plot of Training versus Testing errors using a Precision metric (actually 1.0-precision, so lower is better) that shows how easy it is to over-fit a decision tree to the detriment of generalisation. It is important to check that a classifier isn’t overfitting to the training data such that it is just learning […]
11 years ago

Visualising the internals of Logistic Regression on a Text Matrix

Below I have some plots that visualise the term matrix (as a binary matrix and as a TF-IDF matrix) for the brand disambiguation project followed by a visualisation of the coefficients used in scikit-learn’s LogisticRegression classifier using l1 and l2 penalties. Using a CountVectorizer with binary=True we can mark the absence or presence of a […]
12 years ago

Headroid1 – a face tracking robot head

The video below introduces Headroid1, this face-tracking robot will grow into a larger system that can follow people’s faces, detect emotions and react to engage with the visitor. The above system uses openCV’s face detection (using the Python bindings and facedetect.py) to figure out whether the face is in the centre of the screen, if […]
15 years ago