csvsc 0.1.0

Build processing chains for CSV files
Documentation 
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

use super::{Aggregate, AggregateError};
use crate::{Headers, Row};

#[derive(Default, Debug)]
pub struct Avg {
    source: String,
    colname: String,
    sum: f64,
    count: u64,
}

impl Avg {
    pub fn new(colname: &str, source: &str) -> Avg {
        Avg {
            source: source.to_string(),
            colname: colname.to_string(),
            ..Default::default()
        }
    }
}

impl Aggregate for Avg {
    fn update(&mut self, headers: &Headers, row: &Row) -> Result<(), AggregateError> {
        match headers.get_field(row, &self.source) {
            Some(data) => match data.parse::<f64>() {
                Ok(num) => {
                    self.sum += num;
                    self.count += 1;

                    Ok(())
                }
                Err(_) => Err(AggregateError::ValueError {
                    row: row.clone(),
                    index: headers.index(&self.source).unwrap(),
                    aggregate: "avg".to_string(),
                }),
            },
            None => Err(AggregateError::MissingColumn(self.source.to_string())),
        }
    }

    fn value(&self) -> String {
        if self.count != 0 {
            (self.sum / self.count as f64).to_string()
        } else {
            "NaN".to_string()
        }
    }

    fn colname(&self) -> &str {
        &self.colname
    }
}

#[cfg(test)]
mod tests {
    use super::{Aggregate, AggregateError, Avg};
    use crate::{Headers, Row};

    #[test]
    fn test_avg() {
        let mut avg = Avg::new("new", "a");
        let h = Headers::from_row(Row::from(vec!["a"]));

        let r = Row::from(vec!["3.0"]);
        avg.update(&h, &r).unwrap();
        let r = Row::from(vec!["2"]);
        avg.update(&h, &r).unwrap();
        let r = Row::from(vec![".5"]);
        avg.update(&h, &r).unwrap();
        let r = Row::from(vec![".5"]);
        avg.update(&h, &r).unwrap();

        assert_eq!(avg.value(), "1.5");
    }

    #[test]
    fn test_missing_column() {
        let mut avg = Avg::new("new", "a");
        let h = Headers::from_row(Row::from(vec!["b"]));

        let r = Row::from(vec!["3.0"]);

        match avg.update(&h, &r) {
            Err(AggregateError::MissingColumn(val)) => assert_eq!(val, "a"),
            _ => panic!("Test failed"),
        }
    }

    #[test]
    fn test_value_error() {
        let mut avg = Avg::new("new", "a");
        let h = Headers::from_row(Row::from(vec!["a"]));

        let r = Row::from(vec!["chicken"]);

        match avg.update(&h, &r) {
            Err(AggregateError::ValueError{index, ..}) => assert_eq!(index, 0),
            _ => panic!("Test failed"),
        }
    }
}