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Update random number examples to match new 1.20 semantics

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Fixes #506
This commit is contained in:
Eli Bendersky
2024-01-31 05:08:06 -08:00
parent da72468520
commit f7256dea96
4 changed files with 24 additions and 73 deletions
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22
examples/random-numbers/random-numbers.go
View File

@@ -7,7 +7,6 @@ package main
import (
"fmt"
"math/rand"
"time"
)
func main() {
@@ -28,22 +27,10 @@ func main() {
fmt.Print((rand.Float64() * 5) + 5)
fmt.Println()
// The default number generator is deterministic, so it'll
// produce the same sequence of numbers each time by default.
// To produce varying sequences, give it a seed that changes.
// Note that this is not safe to use for random numbers you
// intend to be secret; use `crypto/rand` for those.
s1 := rand.NewSource(time.Now().UnixNano())
r1 := rand.New(s1)
// Call the resulting `rand.Rand` just like the
// functions on the `rand` package.
fmt.Print(r1.Intn(100), ",")
fmt.Print(r1.Intn(100))
fmt.Println()
// If you seed a source with the same number, it
// produces the same sequence of random numbers.
// If you want a known seed, `NewSource` returns
// a `rand.Source` value that can be used to
// seed a new generator. The same seed will produce
// the same sequence of random numbers.
s2 := rand.NewSource(42)
r2 := rand.New(s2)
fmt.Print(r2.Intn(100), ",")
@@ -53,4 +40,5 @@ func main() {
r3 := rand.New(s3)
fmt.Print(r3.Intn(100), ",")
fmt.Print(r3.Intn(100))
fmt.Println()
}

4
examples/random-numbers/random-numbers.hash
View File

@@ -1,2 +1,2 @@
ea6a386e4e5602247b2203fa433d4419ff5a9489
Enb5uJEx0Bt
1106f890032a51d24bb0a01d7e234c29b4fce005
Op7Udbk3k8K

15
examples/random-numbers/random-numbers.sh
View File

@@ -1,17 +1,12 @@
# Depending on where you run this sample, some of the
# generated numbers may be different. Note that on
# the Go playground seeding with `time.Now()` still
# produces deterministic results due to the way the
# playground is implemented.
# Some of the generated numbers may be
# different when you run the sample.
$ go run random-numbers.go
81,87
0.6645600532184904
7.123187485356329,8.434115364335547
0,28
44,20
0.8090228139659177
5.840125017402497,6.937056298890035
5,87
5,87
# See the [`math/rand`](https://pkg.go.dev/math/rand)
# package docs for references on other random quantities
# that Go can provide.

56
public/random-numbers generated
View File

@@ -43,7 +43,7 @@ generation.</p>
</td>
<td class="code leading">
<a href="https://go.dev/play/p/Enb5uJEx0Bt"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
<a href="https://go.dev/play/p/Op7Udbk3k8K"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
<pre class="chroma"><code><span class="line"><span class="cl"><span class="kn">package</span> <span class="nx">main</span></span></span></code></pre>
</td>
</tr>
@@ -57,7 +57,6 @@ generation.</p>
<pre class="chroma"><code><span class="line"><span class="cl"><span class="kn">import</span> <span class="p">(</span>
</span></span><span class="line"><span class="cl"> <span class="s">&#34;fmt&#34;</span>
</span></span><span class="line"><span class="cl"> <span class="s">&#34;math/rand&#34;</span>
</span></span><span class="line"><span class="cl"> <span class="s">&#34;time&#34;</span>
</span></span><span class="line"><span class="cl"><span class="p">)</span></span></span></code></pre>
</td>
</tr>
@@ -114,38 +113,10 @@ other ranges, for example <code>5.0 &lt;= f' &lt; 10.0</code>.</p>
<tr>
<td class="docs">
<p>The default number generator is deterministic, so it&rsquo;ll
produce the same sequence of numbers each time by default.
To produce varying sequences, give it a seed that changes.
Note that this is not safe to use for random numbers you
intend to be secret; use <code>crypto/rand</code> for those.</p>
</td>
<td class="code leading">
<pre class="chroma"><code><span class="line"><span class="cl"> <span class="nx">s1</span> <span class="o">:=</span> <span class="nx">rand</span><span class="p">.</span><span class="nf">NewSource</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nf">Now</span><span class="p">().</span><span class="nf">UnixNano</span><span class="p">())</span>
</span></span><span class="line"><span class="cl"> <span class="nx">r1</span> <span class="o">:=</span> <span class="nx">rand</span><span class="p">.</span><span class="nf">New</span><span class="p">(</span><span class="nx">s1</span><span class="p">)</span></span></span></code></pre>
</td>
</tr>
<tr>
<td class="docs">
<p>Call the resulting <code>rand.Rand</code> just like the
functions on the <code>rand</code> package.</p>
</td>
<td class="code leading">
<pre class="chroma"><code><span class="line"><span class="cl"> <span class="nx">fmt</span><span class="p">.</span><span class="nf">Print</span><span class="p">(</span><span class="nx">r1</span><span class="p">.</span><span class="nf">Intn</span><span class="p">(</span><span class="mi">100</span><span class="p">),</span> <span class="s">&#34;,&#34;</span><span class="p">)</span>
</span></span><span class="line"><span class="cl"> <span class="nx">fmt</span><span class="p">.</span><span class="nf">Print</span><span class="p">(</span><span class="nx">r1</span><span class="p">.</span><span class="nf">Intn</span><span class="p">(</span><span class="mi">100</span><span class="p">))</span>
</span></span><span class="line"><span class="cl"> <span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">()</span></span></span></code></pre>
</td>
</tr>
<tr>
<td class="docs">
<p>If you seed a source with the same number, it
produces the same sequence of random numbers.</p>
<p>If you want a known seed, <code>NewSource</code> returns
a <code>rand.Source</code> value that can be used to
seed a new generator. The same seed will produce
the same sequence of random numbers.</p>
</td>
<td class="code">
@@ -159,6 +130,7 @@ produces the same sequence of random numbers.</p>
</span></span><span class="line"><span class="cl"> <span class="nx">r3</span> <span class="o">:=</span> <span class="nx">rand</span><span class="p">.</span><span class="nf">New</span><span class="p">(</span><span class="nx">s3</span><span class="p">)</span>
</span></span><span class="line"><span class="cl"> <span class="nx">fmt</span><span class="p">.</span><span class="nf">Print</span><span class="p">(</span><span class="nx">r3</span><span class="p">.</span><span class="nf">Intn</span><span class="p">(</span><span class="mi">100</span><span class="p">),</span> <span class="s">&#34;,&#34;</span><span class="p">)</span>
</span></span><span class="line"><span class="cl"> <span class="nx">fmt</span><span class="p">.</span><span class="nf">Print</span><span class="p">(</span><span class="nx">r3</span><span class="p">.</span><span class="nf">Intn</span><span class="p">(</span><span class="mi">100</span><span class="p">))</span>
</span></span><span class="line"><span class="cl"> <span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">()</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre>
</td>
</tr>
@@ -169,20 +141,16 @@ produces the same sequence of random numbers.</p>
<tr>
<td class="docs">
<p>Depending on where you run this sample, some of the
generated numbers may be different. Note that on
the Go playground seeding with <code>time.Now()</code> still
produces deterministic results due to the way the
playground is implemented.</p>
<p>Some of the generated numbers may be
different when you run the sample.</p>
</td>
<td class="code leading">
<pre class="chroma"><code><span class="line"><span class="cl"><span class="gp">$</span> go run random-numbers.go
</span></span><span class="line"><span class="cl"><span class="go">81,87
</span></span></span><span class="line"><span class="cl"><span class="go">0.6645600532184904
</span></span></span><span class="line"><span class="cl"><span class="go">7.123187485356329,8.434115364335547
</span></span></span><span class="line"><span class="cl"><span class="go">0,28
</span></span><span class="line"><span class="cl"><span class="go">44,20
</span></span></span><span class="line"><span class="cl"><span class="go">0.8090228139659177
</span></span></span><span class="line"><span class="cl"><span class="go">5.840125017402497,6.937056298890035
</span></span></span><span class="line"><span class="cl"><span class="go">5,87
</span></span></span><span class="line"><span class="cl"><span class="go">5,87</span></span></span></code></pre>
</td>
@@ -216,7 +184,7 @@ that Go can provide.</p>
</div>
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codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A \"fmt\"\u000A \"math/rand\"\u000A \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push(' fmt.Print(rand.Intn(100), \",\")\u000A fmt.Print(rand.Intn(100))\u000A fmt.Println()\u000A');codeLines.push(' fmt.Println(rand.Float64())\u000A');codeLines.push(' fmt.Print((rand.Float64()*5)+5, \",\")\u000A fmt.Print((rand.Float64() * 5) + 5)\u000A fmt.Println()\u000A');codeLines.push(' s1 :\u003D rand.NewSource(time.Now().UnixNano())\u000A r1 :\u003D rand.New(s1)\u000A');codeLines.push(' fmt.Print(r1.Intn(100), \",\")\u000A fmt.Print(r1.Intn(100))\u000A fmt.Println()\u000A');codeLines.push(' s2 :\u003D rand.NewSource(42)\u000A r2 :\u003D rand.New(s2)\u000A fmt.Print(r2.Intn(100), \",\")\u000A fmt.Print(r2.Intn(100))\u000A fmt.Println()\u000A s3 :\u003D rand.NewSource(42)\u000A r3 :\u003D rand.New(s3)\u000A fmt.Print(r3.Intn(100), \",\")\u000A fmt.Print(r3.Intn(100))\u000A}\u000A');codeLines.push('');codeLines.push('');
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