Fix infer_schema_length: nil option #600
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Remove additional fallback to the default value of 1000
awerment
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May 23, 2023
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| assert_raise RuntimeError, ~r/from_csv failed:/, fn -> | ||
| DF.from_csv!(csv, infer_schema_length: nil, max_rows: 10) | ||
| end |
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The reason why this second case causes a RuntimeError is that there are no guarantees with max_rows, as documented here.
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Currently, setting
infer_schema_length: nilwhen creating aDataFramefrom CSV has no effect, because there is a redundant fallback to the default value of 1000 rows if themax_rowsoption is not set (or set tonil).Effectively, it is not possible to use all rows for schema inference without setting
infer_schema_length(ormax_rows) to a large enough "guess". I believe this does not match the documented behavior:This PR removes the fallback to the default.
I'm not sure if the changes here are actually preferable to changing the docs, as scanning all rows will be slow for larger files (as stated), but ran into an issue myself with the following situation:
infer_schema_length/max_rowsvalue felt wrong)Nk lines contain0, later lines contain float values. (an issue with the source of the files, but fixing that is not possible)