A blog of Python-related topics and code.
Changes in real wages since 2007
Posted by: christian 1 year, 1 month ago
The OECD provides a tool for studying the change in average real wages (compared in purchase power parity adjusted US dollars using a 2012 base year). Here is how real wages have changed in 15 countries, visualised on a bar chart visualized with Matplotlib.
Determining mean bond lengths from crystallographic data
Posted by: christian 1 year, 3 months ago
The Cambridge Crystallographic Data Centre is a non-profit organisation devoted to small-molecule crystallography data. It curates, validates and distributes the Cambridge Structural Database (CSD) of over 800,000 organic and metal-organic crystal structures. The CSD has an excellent Python API which can be used to analyse these structures. Unfortunately, access to most of the CCDC data requires a paid-for licence or an institutional subscription. In the short project below I obtained the necessary crystal structures using my UCL credentials. Installation and configuration of the database and software is documented on the CCDC website.
Visualizing the gradient descent method
Posted by: christian 1 year, 3 months ago
In the gradient descent method of optimization, a hypothesis function, $h_\boldsymbol{\theta}(x)$, is fitted to a data set, $(x^{(i)}, y^{(i)})$ ($i=1,2,\cdots,m$) by minimizing an associated cost function, $J(\boldsymbol{\theta})$ in terms of the parameters $\boldsymbol\theta = \theta_0, \theta_1, \cdots$. The cost function describes how closely the hypothesis fits the data for a given choice of $\boldsymbol \theta$.
The Earth-Venus "dance"
Posted by: christian 1 year, 3 months ago
If you join the positions of Earth and Venus with a straight line and follow them as they orbit the sun, you get a nice picture that has been popular on Facebook. Here's the Python code for generating a similar diagram. The figure has the pleasing shape it does because the ratio of the planets' orbital periods is close to 13:8.
Has the end of April 2016 been unusually cold?
Posted by: christian 1 year, 4 months ago
It's certainly been colder than usual in Britain over the last couple of weeks. How unusual is it to have these temperatures at the end of April?