CodingLevel 2
Data and ML code
Easynot started
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Strings & parsingParsing turns a raw sequence of characters into meaningful chunks and evaluates them step by step.3 minML primitives from scratchFundamental algorithms like K-Means are just math loops on vectors.3 minDataframesStop walking rows one at a time, describe the rows you want and hand the whole description to the table.5 minGROUP BY and aggregationMany rows walk into a bucket; one row walks out, carrying the totals.5 minReading a log fileSplit off the fixed fields, keep the message whole, then key it and count.4 minParsing configuration filesA config file is a tiny language, and almost every bug in reading one is a splitting bug.4 minJoins that keep the right rowsA join is a question about rows: which ones survive, and what fills the gaps when there's no match.4 minDatabase aggregationTurning millions of rows into a single summary table using math.3 minHow a domain name is encoded on the wireA domain isn't sent as text with dots, each label gets a length byte, and the dots disappear.3 minHTTP range requestsDon't re-download the whole file, ask the server for just the bytes you're missing.3 minThe User-Agent headerA free-form string your client mumbles on every request: "hi, I'm this browser, on this OS", and the server tries to make sense of it.4 minOnline learningUpdating a machine learning model's brain in real-time, one data point at a time.3 minParsing CSV, character by characterA comma is only a separator until it's inside quotes, so you parse with a state machine, not split().3 min