![]() ![]() The function takes either a string or Path and turns it into a tuple of parts that should look a bit like this: (,, ,, ) Match structure : case ( "cpi", country_code, "by-month", date, filename ) if ( len ( country_code ) = 2 and re. I won’t cover the hypothetical parsing itself, but Python Pattern Matching Examples: ETL and Dataclasses lays out an example that shows you how you can.ĭef parse_ts_structure ( filepath : str | Path ) : structure = Path ( filepath ). Let’s flesh out a few skeleton functions that do the latter. So in the example above, the country field is something we cannot wish away or pretend will work everywhere. ![]() The vast majority of “structured” data, like CPI indices, vary greatly by the body responsible for generating them - and there may well be more than one source of truth. The first consideration – as this is just an example – is separating the logic that parses the file paths from the logic that processes the files. ![]() Dispatching to the correct reader by country So let’s look at a way that will scale using the match and case keywords. Ordinarily, you’d just split the path and write some quick logic that picks out what you need, and that’ll work fine for simple things, but if you have to deal with dozens of variadic fields in the file path, that approach will not scale. Where cpi means Consumer Price Index country is the ISO-3166 code for a country yyyy-mm-dd is the ISO date for the particular month yyyy-qq is the year and quarter and filename is an arbitrary filename and ext is an extension. Contextualizing that information is usually done with a mixture of if statements and liberal use of pathlib’s Path or os.path, but the structural pattern matching feature in Python 3.10 is there to cut down on the tedium.Ĭonsider a directory structure that looks a bit like this: cpi//by-month//. It is a common activity, particularly in data science where the file structure may contain important semantic clues like a date or the source of the data. Manipulating file and path strings is dreary work. ![]()
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