Saturday, April 08, 2023

kdb+/q - Converting a CSV String into a Table

I often find myself wanting to create quick in-memory tables in q for testing purposes. The usual way to create a table is by specifying lists of column names and values, or flipping a dictionary, as shown below:

([] name:`Alice`Bob`Charles;age:20 30 40;city:`London`Paris`Athens)

// or, using a dictionary:

flip `name`age`city!(`Alice`Bob`Charles;20 30 40;`London`Paris`Athens)

As you can see, it's quite difficult to visualise the table being created using this approach. That's why I sometimes prefer to create a table from a multi-line CSV string instead, using the 0: operator, as shown below:

("SIS";enlist",") 0:

name    age city
Alice   20  London
Bob     30  Paris
Charles 40  Athens

Note that you can also load from a CSV file:

("SIS";enlist",") 0: `$"/path/to/file.csv"
Related post:
kdb+/q - Reading and Writing a CSV File

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