-
Notifications
You must be signed in to change notification settings - Fork 70
/
partition.rs
235 lines (209 loc) · 8.32 KB
/
partition.rs
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
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
static USAGE: &str = r#"
Partitions the given CSV data into chunks based on the value of a column.
See `split` command to split a CSV data by row count, by number of chunks or
by kb-size.
The files are written to the output directory with filenames based on the
values in the partition column and the `--filename` flag.
EXAMPLE:
Partition nyc311.csv file into separate files based on the value of the
"Borough" column in the current directory:
$ qsv partition Borough . --filename "nyc311-{}.csv" nyc311.csv
will create the following files, each containing the data for each borough:
nyc311-Bronx.csv
nyc311-Brooklyn.csv
nyc311-Manhattan.csv
nyc311-Queens.csv
nyc311-Staten_Island.csv
For more examples, see https://github.com/jqnatividad/qsv/blob/master/tests/test_partition.rs.
Usage:
qsv partition [options] <column> <outdir> [<input>]
qsv partition --help
partition arguments:
<column> The column to use as a key for partitioning.
You can use the `--select` option to select
the column by name or index, but only one
column can be used for partitioning.
See `select` command for more details.
<outdir> The directory to write the output files to.
<input> The CSV file to read from. If not specified, then
the input will be read from stdin.
partition options:
--filename <filename> A filename template to use when constructing the
names of the output files. The string '{}' will
be replaced by a value based on the partition column,
but sanitized for shell safety.
[default: {}.csv]
-p, --prefix-length <n> Truncate the partition column after the
specified number of bytes when creating the
output file.
--drop Drop the partition column from results.
Common options:
-h, --help Display this message
-n, --no-headers When set, the first row will NOT be interpreted
as column names. Otherwise, the first row will
appear in all chunks as the header row.
-d, --delimiter <arg> The field delimiter for reading CSV data.
Must be a single character. (default: ,)
"#;
use std::{
collections::{hash_map::Entry, HashSet},
fs, io,
path::Path,
};
use ahash::AHashMap;
use regex::Regex;
use serde::Deserialize;
use crate::{
config::{Config, Delimiter},
select::SelectColumns,
util::{self, FilenameTemplate},
CliResult,
};
#[derive(Clone, Deserialize)]
struct Args {
arg_column: SelectColumns,
arg_input: Option<String>,
arg_outdir: String,
flag_filename: FilenameTemplate,
flag_prefix_length: Option<usize>,
flag_drop: bool,
flag_no_headers: bool,
flag_delimiter: Option<Delimiter>,
}
pub fn run(argv: &[&str]) -> CliResult<()> {
let args: Args = util::get_args(USAGE, argv)?;
fs::create_dir_all(&args.arg_outdir)?;
// It would be nice to support efficient parallel partitions, but doing
// so would involve more complicated inter-thread communication, with
// multiple readers and writers, and some way of passing buffers
// between them.
args.sequential_partition()
}
impl Args {
/// Configuration for our reader.
fn rconfig(&self) -> Config {
Config::new(&self.arg_input)
.delimiter(self.flag_delimiter)
.no_headers(self.flag_no_headers)
.select(self.arg_column.clone())
}
/// Get the column to use as a key.
#[allow(clippy::unused_self)]
fn key_column(&self, rconfig: &Config, headers: &csv::ByteRecord) -> CliResult<usize> {
let select_cols = rconfig.selection(headers)?;
if select_cols.len() == 1 {
Ok(select_cols[0])
} else {
fail!("can only partition on one column")
}
}
/// A basic sequential partition.
fn sequential_partition(&self) -> CliResult<()> {
let rconfig = self.rconfig();
let mut rdr = rconfig.reader()?;
let headers = rdr.byte_headers()?.clone();
let key_col = self.key_column(&rconfig, &headers)?;
let mut gen = WriterGenerator::new(self.flag_filename.clone());
let mut writers: AHashMap<Vec<u8>, BoxedWriter> = AHashMap::new();
let mut row = csv::ByteRecord::new();
while rdr.read_byte_record(&mut row)? {
// Decide what file to put this in.
let column = &row[key_col];
let key = match self.flag_prefix_length {
// We exceed --prefix-length, so ignore the extra bytes.
Some(len) if len < column.len() => &column[0..len],
_ => column,
};
let mut entry = writers.entry(key.to_vec());
let wtr =
match entry {
Entry::Occupied(ref mut occupied) => occupied.get_mut(),
Entry::Vacant(vacant) => {
// We have a new key, so make a new writer.
let mut wtr = gen.writer(&*self.arg_outdir, key)?;
if !rconfig.no_headers {
if self.flag_drop {
wtr.write_record(headers.iter().enumerate().filter_map(
|(i, e)| if i == key_col { None } else { Some(e) },
))?;
} else {
wtr.write_record(&headers)?;
}
}
vacant.insert(wtr)
},
};
if self.flag_drop {
wtr.write_record(row.iter().enumerate().filter_map(|(i, e)| {
if i == key_col {
None
} else {
Some(e)
}
}))?;
} else {
wtr.write_byte_record(&row)?;
}
wtr.flush()?;
}
Ok(())
}
}
type BoxedWriter = csv::Writer<Box<dyn io::Write + 'static>>;
/// Generates unique filenames based on CSV values.
struct WriterGenerator {
template: FilenameTemplate,
counter: usize,
used: HashSet<String>,
non_word_char: Regex,
}
impl WriterGenerator {
fn new(template: FilenameTemplate) -> WriterGenerator {
WriterGenerator {
template,
counter: 1,
used: HashSet::new(),
non_word_char: Regex::new(r"\W").unwrap(),
}
}
/// Create a CSV writer for `key`. Does not add headers.
fn writer<P>(&mut self, path: P, key: &[u8]) -> io::Result<BoxedWriter>
where
P: AsRef<Path>,
{
let unique_value = self.unique_value(key);
self.template.writer(path.as_ref(), &unique_value)
}
/// Generate a unique value for `key`, suitable for use in a
/// "shell-safe" filename. If you pass `key` twice, you'll get two
/// different values.
fn unique_value(&mut self, key: &[u8]) -> String {
// Sanitize our key.
let utf8 = String::from_utf8_lossy(key);
let safe = self.non_word_char.replace_all(&utf8, "").into_owned();
let base = if safe.is_empty() {
"empty".to_owned()
} else {
safe
};
// Now check for collisions.
if self.used.contains(&base) {
loop {
let candidate = format!("{}_{}", &base, self.counter);
self.counter = self.counter.checked_add(1).unwrap_or_else(|| {
// We'll run out of other things long before we ever
// reach this, but we'll check just for correctness and
// completeness.
panic!("Cannot generate unique value")
});
if !self.used.contains(&candidate) {
self.used.insert(candidate.clone());
return candidate;
}
}
} else {
self.used.insert(base.clone());
base
}
}
}