add a describe method on DataFrame like Polars #5226
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Try to complete this work, there are still many places that can be optimized. |
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make describe method return right datatype for record batch。
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| if field.data_type().is_numeric() { | ||
| Field::new(field.name(), DataType::Float64, true) | ||
| } else { | ||
| Field::new(field.name(), DataType::Utf8, true) |
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I would expect that the schema for count and null_count were always Int64 and the schema for min/max were always Utf8
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the describe method return schema like this.
the each column should have same datatype .
for example :
bool_coloncount/null_countreturn Int64 ; error onmin/max, so makebool_coldatatypeUTF8;float_coloncount/null_countreturn Int64 ; onmin/maxreturn float, so makefloat_coldatatypeFloat64
datafusion/core/src/dataframe.rs
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| vec![], | ||
| fields_iter | ||
| .clone() | ||
| .filter(|f| matches!(f.data_type().is_numeric(), true)) |
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I wonder why restrict the min/max aggregation to numeric fields?
In order to get the min/max values in all columns to work, you could call cast to cast them to the same datatype
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boolean and binary not work with min/max.
filter out DataType::Binary , DataType::Boolean will be better.
!matches!(f.data_type(), DataType::Binary | DataType::Boolean)
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date_string_col, string_col ’s datatype also Binary.
called Result::unwrap() on an Err value: Internal("Min/Max accumulator not implemented for type Binary")
alamb
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Looks good to me -- thank you @jiangzhx
cc @andygrove (as I think this is a neat thing to expose in datafusion-python)
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| let describe_record_batch = |
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Benchmark runs are scheduled for baseline = ea3b965 and contender = 96aa2a6. 96aa2a6 is a master commit associated with this PR. Results will be available as each benchmark for each run completes. |
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Which issue does this PR close?
Closes #4974 .