Infer schemas and coerce data for table cells #346
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src/table.js
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| case "boolean": | ||
| if (typeof value === "string") { | ||
| const trimValue = value.trim(); | ||
| return trimValue === "true" ? true : trimValue === "false" ? false : null; |
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Just want to note that I was surprised that our boolean coercion returned false for a column of string values, but true for other types, such as a column of empty objects. Maybe the default return value for strings should be Boolean(value), but then that ruins detecting the strings "true" and "false".
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It returned null for string values (rather than false). I'm not sure what the right response is when a Date, object, or other types are coerced to boolean. TRUE seems surprising to me, but if that's what we want to do, then it does seem strange to have type string alone not conform to that. Any thoughts, @mbostock?
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I think we have to do this because string is special: it’s the “untyped” format we use to serialize other types (namely in CSV).
Co-authored-by: Mike Bostock <[email protected]>
Co-authored-by: Mike Bostock <[email protected]>
Resolves https://github.com/observablehq/observablehq/issues/9862 and https://github.com/observablehq/observablehq/issues/9673
In this inference approach, we take a sample (currently the first 100 rows), and for each column, count how many times we encounter each possible data type. Then, if > 90% of the sampled values conform to that type, we take the most frequently encountered type as the column's type. If not, we use type "other."
These changes include some support for upcoming column type assertions, but for the purposes of this PR, I'm testing against main.
inference_and_coercion.mov