1///
2/// This example parses, sorts and groups the iris dataset
3/// and does some simple manipulations.
4///
5/// Iterators and itertools functionality are used throughout.
6
7use itertools::Itertools;
8use std::collections::HashMap;
9use std::iter::repeat;
10use std::num::ParseFloatError;
11use std::str::FromStr;
12
13static DATA: &'static str = include_str!("iris.data");
14
15#[derive(Clone, Debug)]
16struct Iris {
17 name: String,
18 data: [f32; 4],
19}
20
21#[derive(Clone, Debug)]
22enum ParseError {
23 Numeric(ParseFloatError),
24 Other(&'static str),
25}
26
27impl From<ParseFloatError> for ParseError {
28 fn from(err: ParseFloatError) -> Self {
29 ParseError::Numeric(err)
30 }
31}
32
33/// Parse an Iris from a comma-separated line
34impl FromStr for Iris {
35 type Err = ParseError;
36
37 fn from_str(s: &str) -> Result<Self, Self::Err> {
38 let mut iris = Iris { name: "".into(), data: [0.; 4] };
39 let mut parts = s.split(",").map(str::trim);
40
41 // using Iterator::by_ref()
42 for (index, part) in parts.by_ref().take(4).enumerate() {
43 iris.data[index] = part.parse::<f32>()?;
44 }
45 if let Some(name) = parts.next() {
46 iris.name = name.into();
47 } else {
48 return Err(ParseError::Other("Missing name"))
49 }
50 Ok(iris)
51 }
52}
53
54fn main() {
55 // using Itertools::fold_results to create the result of parsing
56 let irises = DATA.lines()
57 .map(str::parse)
58 .fold_ok(Vec::new(), |mut v, iris: Iris| {
59 v.push(iris);
60 v
61 });
62 let mut irises = match irises {
63 Err(e) => {
64 println!("Error parsing: {:?}", e);
65 std::process::exit(1);
66 }
67 Ok(data) => data,
68 };
69
70 // Sort them and group them
71 irises.sort_by(|a, b| Ord::cmp(&a.name, &b.name));
72
73 // using Iterator::cycle()
74 let mut plot_symbols = "+ox".chars().cycle();
75 let mut symbolmap = HashMap::new();
76
77 // using Itertools::group_by
78 for (species, species_group) in &irises.iter().group_by(|iris| &iris.name) {
79 // assign a plot symbol
80 symbolmap.entry(species).or_insert_with(|| {
81 plot_symbols.next().unwrap()
82 });
83 println!("{} (symbol={})", species, symbolmap[species]);
84
85 for iris in species_group {
86 // using Itertools::format for lazy formatting
87 println!("{:>3.1}", iris.data.iter().format(", "));
88 }
89
90 }
91
92 // Look at all combinations of the four columns
93 //
94 // See https://en.wikipedia.org/wiki/Iris_flower_data_set
95 //
96 let n = 30; // plot size
97 let mut plot = vec![' '; n * n];
98
99 // using Itertools::tuple_combinations
100 for (a, b) in (0..4).tuple_combinations() {
101 println!("Column {} vs {}:", a, b);
102
103 // Clear plot
104 //
105 // using std::iter::repeat;
106 // using Itertools::set_from
107 plot.iter_mut().set_from(repeat(' '));
108
109 // using Itertools::minmax
110 let min_max = |data: &[Iris], col| {
111 data.iter()
112 .map(|iris| iris.data[col])
113 .minmax()
114 .into_option()
115 .expect("Can't find min/max of empty iterator")
116 };
117 let (min_x, max_x) = min_max(&irises, a);
118 let (min_y, max_y) = min_max(&irises, b);
119
120 // Plot the data points
121 let round_to_grid = |x, min, max| ((x - min) / (max - min) * ((n - 1) as f32)) as usize;
122 let flip = |ix| n - 1 - ix; // reverse axis direction
123
124 for iris in &irises {
125 let ix = round_to_grid(iris.data[a], min_x, max_x);
126 let iy = flip(round_to_grid(iris.data[b], min_y, max_y));
127 plot[n * iy + ix] = symbolmap[&iris.name];
128 }
129
130 // render plot
131 //
132 // using Itertools::join
133 for line in plot.chunks(n) {
134 println!("{}", line.iter().join(" "))
135 }
136 }
137}
138