The summary.
R REMAINS BECAUSE ITS STATISTICAL ECOSYSTEM IS UNMATCHED
Many methods appear there first. Analysis frequently happens in R while production systems live elsewhere.
PYTHON WINS WHERE ANALYSIS AND PRODUCTION SHOULD SHARE A LANGUAGE
Which is most machine learning work.
MATLAB PERSISTS BECAUSE ITS TOOLBOXES ARE MATURE, VALIDATED AND ACCEPTED
Cost is what drives people away; existing models and regulatory acceptance are what keep them.
Both R and MATLAB index from one, not zero.
FILTER AND AGGREGATE IN THE DATABASE
Extracting everything and processing it afterwards is far slower.
REPRODUCIBILITY IS THE ACTUAL DISCIPLINE
Record the source, every transformation, the code, library versions and random seeds.
Restart and run a notebook from the top before trusting any result — notebook state depends on execution order, and one that works for its author may not run cleanly.
Keep raw data unmodified, and generate reports from code so figures and text cannot diverge.
WHAT MATTERS MORE THAN THE LANGUAGE CHOICE
Understanding the data, and asking the right question.
