Dev/518/formula

Created by: jassak

• New version of Descriptive Statistics:
  • Adds null/total counts for every variable
  • Replaces variable code with label
  • Removes unnecessary lower/upper confidence intervals
• New formula functionality for Descriptive Statistics and Logistic Regression
  • New formula_description property in algorithm specifications.
  • Descriptive Stats and Logistic Regression now accept a new formula_description argument. This argument expects a description of a formula in Wilkinson notation in JSON format. From the description an actual string formula is constructed and passed to the patsy library from which the algorithm's design matrices are constructed.
  • Currently only a subset of the full Wilkinson notation is implemented. Interactions are up to 3 terms and singleton terms have a limited number of transformations allowed. These are nop, log, exp, center, standardize, mul and div for numerical variables.
• Refactoring of mipframework.
• Modification of algorithm tests for Descriptive Statistics and Logistic Regression to reflect the above changes.
• New tests for the above two algorithms with the addition of the formula argument.