berkaysynnada commented on code in PR #6982:
URL: https://github.com/apache/arrow-datafusion/pull/6982#discussion_r1267969624
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datafusion/physical-expr/src/intervals/interval_aritmetic.rs:
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@@ -1172,4 +1321,70 @@ mod tests {
let upper = 1.5;
capture_mode_change_f32((lower, upper), true, true);
}
+
+ #[test]
+ fn test_cardinality_of_intervals() -> Result<()> {
+ // In IEEE 754 standard for floating-point arithmetic, if we keep the
sign and exponent fields same,
+ // we can represent 4503599627370496 different numbers by changing the
mantissa
+ // (4503599627370496 = 2^52, since there are 52 bits in mantissa, and
2^23 = 8388608 for f32).
+ let distinct_f64 = 4503599627370496;
+ let distinct_f32 = 8388608;
+ let intervals = [
+ Interval::new(
+ IntervalBound::new(ScalarValue::from(0.25), false),
+ IntervalBound::new(ScalarValue::from(0.50), true),
+ ),
+ Interval::new(
+ IntervalBound::new(ScalarValue::from(0.5), false),
+ IntervalBound::new(ScalarValue::from(1.0), true),
+ ),
+ Interval::new(
+ IntervalBound::new(ScalarValue::from(1.0), false),
+ IntervalBound::new(ScalarValue::from(2.0), true),
+ ),
+ Interval::new(
+ IntervalBound::new(ScalarValue::from(32.0), false),
+ IntervalBound::new(ScalarValue::from(64.0), true),
+ ),
+ Interval::new(
+ IntervalBound::new(ScalarValue::from(-0.50), false),
+ IntervalBound::new(ScalarValue::from(-0.25), true),
+ ),
+ Interval::new(
+ IntervalBound::new(ScalarValue::from(-32.0), false),
+ IntervalBound::new(ScalarValue::from(-16.0), true),
+ ),
+ ];
+ for interval in intervals {
+ assert_eq!(interval.cardinality()?, distinct_f64);
+ }
+
+ let intervals = [
+ Interval::new(
+ IntervalBound::new(ScalarValue::from(0.25_f32), false),
+ IntervalBound::new(ScalarValue::from(0.50_f32), true),
+ ),
+ Interval::new(
+ IntervalBound::new(ScalarValue::from(-1_f32), false),
+ IntervalBound::new(ScalarValue::from(-0.5_f32), true),
+ ),
+ ];
+ for interval in intervals {
+ assert_eq!(interval.cardinality()?, distinct_f32);
+ }
+
+ let interval = Interval::new(
+ IntervalBound::new(ScalarValue::from(-0.0625), false),
+ IntervalBound::new(ScalarValue::from(0.0625), true),
+ );
+ assert_eq!(interval.cardinality()?, distinct_f64 * 2_048);
Review Comment:
You are right that it wouldn't have much use in practice, but using the
distinct parameter might be more accurate at an outer scope to calculate
practical cardinalities since we have not introduced statistical metrics like
distribution yet to the library.
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