random option for sort command

Though this overlaps with the new `scramble` command, it's still useful to adapt this PR.

BurntSushi/xsv#185

src/cmd/sort.rs

@@ -4,8 +4,8 @@ use crate::config::{Config, Delimiter};
 use crate::select::SelectColumns;
 use crate::util;
 use crate::CliResult;
+use rand::{seq::SliceRandom, SeedableRng, rngs::StdRng};
 use serde::Deserialize;
-use rand::{thread_rng, Rng, SeedableRng, StdRng};
 use std::str::from_utf8;
 
 use self::Number::{Float, Int};
@@ -46,7 +46,7 @@ struct Args {
     flag_numeric: bool,
     flag_reverse: bool,
     flag_random: bool,
-    flag_seed: Option<usize>,
+    flag_seed: Option<u64>,
     flag_output: Option<String>,
     flag_no_headers: bool,
     flag_delimiter: Option<Delimiter>,
@@ -70,45 +70,39 @@ pub fn run(argv: &[&str]) -> CliResult<()> {
 
     // Seeding rng
     let seed = args.flag_seed;
-    let mut rng: StdRng = match seed {
-        None => {
-            StdRng::from_rng(thread_rng()).unwrap()
-        }
-        Some(seed) => {
-            let mut buf = [0u8; 32];
-            LittleEndian::write_u64(&mut buf, seed as u64);
-            SeedableRng::from_seed(buf)
-        }
-    };
 
     let mut all = rdr.byte_records().collect::<Result<Vec<_>, _>>()?;
     match (numeric, reverse, random) {
-        (_, _, true) =>
-            rng.shuffle(&mut all),
-        (false, false, false) =>
-            all.sort_by(|r1, r2| {
-                let a = sel.select(r1);
-                let b = sel.select(r2);
-                iter_cmp(a, b)
-            }),
-        (true, false, false) =>
-            all.sort_by(|r1, r2| {
-                let a = sel.select(r1);
-                let b = sel.select(r2);
-                iter_cmp_num(a, b)
-            }),
-        (false, true, false) =>
-            all.sort_by(|r1, r2| {
-                let a = sel.select(r1);
-                let b = sel.select(r2);
-                iter_cmp(b, a)
-            }),
-        (true, true, false) =>
-            all.sort_by(|r1, r2| {
-                let a = sel.select(r1);
-                let b = sel.select(r2);
-                iter_cmp_num(b, a)
-            }),
+        (_, _, true) => {
+            //SliceRandom::shuffle(&mut all, &mut rng),
+            if let Some(val) = seed {
+                let mut rng = StdRng::seed_from_u64(val);
+                SliceRandom::shuffle(&mut *all, &mut rng);
+            } else {
+                let mut rng = ::rand::thread_rng();
+                SliceRandom::shuffle(&mut *all, &mut rng);
+            }
+        }
+        (false, false, false) => all.sort_by(|r1, r2| {
+            let a = sel.select(r1);
+            let b = sel.select(r2);
+            iter_cmp(a, b)
+        }),
+        (true, false, false) => all.sort_by(|r1, r2| {
+            let a = sel.select(r1);
+            let b = sel.select(r2);
+            iter_cmp_num(a, b)
+        }),
+        (false, true, false) => all.sort_by(|r1, r2| {
+            let a = sel.select(r1);
+            let b = sel.select(r2);
+            iter_cmp(b, a)
+        }),
+        (true, true, false) => all.sort_by(|r1, r2| {
+            let a = sel.select(r1);
+            let b = sel.select(r2);
+            iter_cmp_num(b, a)
+        }),
     }
 
     let mut wtr = Config::new(&args.flag_output).writer()?;

tests/test_sort.rs

@@ -170,20 +170,31 @@ fn sort_uniq() {
 #[test]
 fn sort_random() {
     let wrk = Workdir::new("sort_random");
-    wrk.create("in.csv", vec![
-        svec!["R", "S"],
-        svec!["1", "b"],
-        svec!["2", "a"],
-    ]);
+    wrk.create(
+        "in.csv",
+        vec![
+            svec!["R", "S"],
+            svec!["1", "b"],
+            svec!["2", "a"],
+            svec!["3", "d"],
+            svec!["4", "c"],
+            svec!["5", "f"],
+            svec!["6", "e"],
+        ],
+    );
 
     let mut cmd = wrk.command("sort");
-    cmd.arg("--random").args(&["--seed", "0"]).arg("in.csv");
+    cmd.arg("--random").args(&["--seed", "42"]).arg("in.csv");
 
     let got: Vec<Vec<String>> = wrk.read_stdout(&mut cmd);
     let expected = vec![
         svec!["R", "S"],
-        svec!["2", "a"],
         svec!["1", "b"],
+        svec!["5", "f"],
+        svec!["6", "e"],
+        svec!["3", "d"],
+        svec!["2", "a"],
+        svec!["4", "c"],
     ];
     assert_eq!(got, expected);
 }