invr 0.2.3

Declarative data validation engine using invariants executed on Polars DataFrames.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144

use crate::infrastructure::polars::kind::PolarsKind;
use crate::invariant::Invariant;
use crate::scope::Scope;
use crate::violation::Violation;
use crate::violation::value_object::metric_value::MetricValue;
use polars::prelude::AnyValue;
use polars::prelude::*;

/// Builds the Polars expression computing the requested percentile
/// for the target numeric column.
///
/// Required parameters:
/// - `p`: percentile as a float between 0.0 and 1.0
///
/// Scope:
/// - Requires `Scope::Column`
///
/// Behavior:
/// - Uses Polars `quantile()` with `QuantileMethod::Nearest`
/// - Returns a single scalar representing the computed percentile value
///
/// The resulting metric represents the raw percentile value
/// (it is NOT validated against bounds at this stage).
pub fn plan(inv: &Invariant<PolarsKind>) -> Option<Expr> {
    let Scope::Column { name } = inv.scope() else {
        return None;
    };

    let p: f64 = inv.require_param("p").ok()?.parse().ok()?;

    Some(col(name).quantile(lit(p), QuantileMethod::Nearest))
}

/// Converts the computed percentile value into a bounded-range violation.
///
/// Required parameters:
/// - `min`: minimum allowed percentile value (inclusive)
/// - `max`: maximum allowed percentile value (inclusive)
///
/// Logic:
/// - Reads the computed percentile value
/// - Returns a violation if `percentile < min` OR `percentile > max`
///
/// Produced metric:
/// - `percentile_value` (float)
pub fn map(inv: &Invariant<PolarsKind>, value: AnyValue) -> Option<Violation> {
    let percentile = value.try_extract::<f64>().ok()?;

    let min: f64 = inv.require_param("min").ok()?.parse().ok()?;
    let max: f64 = inv.require_param("max").ok()?.parse().ok()?;

    if percentile < min || percentile > max {
        Some(
            Violation::new(
                inv.id().clone(),
                inv.severity(),
                inv.scope().clone(),
                format!("percentile out of range: {percentile}"),
            )
            .with_metric("percentile_value", MetricValue::Float(percentile)),
        )
    } else {
        None
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::domain::invariant::value_object::id::InvariantId;
    use std::collections::BTreeMap;

    fn make_invariant(p: f64, min: f64, max: f64) -> Invariant<PolarsKind> {
        let id = InvariantId::new("percentile_between_test").unwrap();
        let mut params = BTreeMap::new();
        params.insert("p".to_string(), p.to_string());
        params.insert("min".to_string(), min.to_string());
        params.insert("max".to_string(), max.to_string());

        Invariant::new(
            id,
            PolarsKind::PercentileBetween,
            Scope::Column {
                name: "a".to_string(),
            },
        )
        .with_params(params)
    }

    fn df(values: Vec<f64>) -> DataFrame {
        let height = values.len();
        let series = Series::new("a".into(), values);
        DataFrame::new(height, vec![series.into()]).unwrap()
    }

    #[test]
    fn test_plan_returns_expr() {
        let inv = make_invariant(0.5, 0.0, 100.0);
        assert!(plan(&inv).is_some());
    }

    #[test]
    fn test_percentile_no_violation() {
        let values = vec![1.0, 2.0, 3.0, 4.0, 5.0];
        let df = df(values);
        let inv = make_invariant(0.5, 2.0, 4.0); // median should be 3

        let result = df.lazy().select([plan(&inv).unwrap()]).collect().unwrap();

        let val = result.columns()[0]
            .get(0)
            .unwrap()
            .try_extract::<f64>()
            .unwrap();

        assert!(map(&inv, AnyValue::Float64(val)).is_none());
    }

    #[test]
    fn test_percentile_violation_out_of_range() {
        let values = vec![1.0, 2.0, 3.0, 4.0, 5.0];
        let df = df(values);
        let inv = make_invariant(0.5, 4.5, 10.0); // median = 3, below min

        let result = df.lazy().select([plan(&inv).unwrap()]).collect().unwrap();

        let val = result.columns()[0]
            .get(0)
            .unwrap()
            .try_extract::<f64>()
            .unwrap();

        let violation = map(&inv, AnyValue::Float64(val));
        assert!(violation.is_some());
    }

    #[test]
    fn test_wrong_scope_returns_none() {
        let id = InvariantId::new("wrong_scope").unwrap();
        let inv = Invariant::new(id, PolarsKind::PercentileBetween, Scope::Dataset);

        assert!(plan(&inv).is_none());
    }
}