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typo in article about base R
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@etiennebacher
etiennebacher committed Aug 22, 2023
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2 changes: 1 addition & 1 deletion ...2-11-28-some-notes-about-improving-base-r-code/some-notes-about-improving-base-r-code.Rmd
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Expand Up @@ -60,7 +60,7 @@ quite inefficient: it would be enough to stop as soon as we find two different
values.

What we can do is to compare all values to the first value of the vector. Below is
an example with a vector containing 1 million values. In the first case, it only
an example with a vector containing 10 million values. In the first case, it only
contains `1`, and in the second case it contains `1` and `2`.

```{r}
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41 changes: 19 additions & 22 deletions ...-11-28-some-notes-about-improving-base-r-code/some-notes-about-improving-base-r-code.html
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Expand Up @@ -2417,7 +2417,7 @@ <h2 id="check-if-a-vector-has-a-single-value">Check if a vector has a single val
quite inefficient: it would be enough to stop as soon as we find two different
values.</p>
<p>What we can do is to compare all values to the first value of the vector. Below is
an example with a vector containing 1 million values. In the first case, it only
an example with a vector containing 10 million values. In the first case, it only
contains <code>1</code>, and in the second case it contains <code>1</code> and <code>2</code>.</p>
<div class="layout-chunk" data-layout="l-body">
<div class="sourceCode">
Expand All @@ -2431,11 +2431,10 @@ <h2 id="check-if-a-vector-has-a-single-value">Check if a vector has a single val
<span><span class="op">)</span></span></code></pre>
</div>
<pre><code># A tibble: 2 × 6
expression min median itr/se…¹ mem_a…² gc/se…³
&lt;bch:expr&gt; &lt;bch:tm&gt; &lt;bch:tm&gt; &lt;dbl&gt; &lt;bch:b&gt; &lt;dbl&gt;
1 length(unique(test)) == 1 249.1ms 280ms 3.50 166.1MB 3.50
2 all(test == test[1]) 52.3ms 54ms 17.2 38.1MB 3.45
# … with abbreviated variable names ¹​`itr/sec`, ²​mem_alloc, ³​`gc/sec`</code></pre>
expression min median `itr/sec` mem_alloc `gc/sec`
&lt;bch:expr&gt; &lt;bch:t&gt; &lt;bch:t&gt; &lt;dbl&gt; &lt;bch:byt&gt; &lt;dbl&gt;
1 length(unique(test)) =… 161.8ms 185.6ms 5.31 166.1MB 5.31
2 all(test == test[1]) 44.2ms 69.7ms 14.9 38.1MB 4.47</code></pre>
<div class="sourceCode">
<pre class="sourceCode r"><code class="sourceCode r"><span><span class="co"># Should be FALSE</span></span>
<span><span class="va">test2</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/base/rep.html">rep</a></span><span class="op">(</span><span class="fu"><a href="https://rdrr.io/r/base/c.html">c</a></span><span class="op">(</span><span class="fl">1</span>, <span class="fl">2</span><span class="op">)</span>, <span class="fl">1e7</span><span class="op">)</span></span>
Expand All @@ -2447,11 +2446,10 @@ <h2 id="check-if-a-vector-has-a-single-value">Check if a vector has a single val
<span><span class="op">)</span></span></code></pre>
</div>
<pre><code># A tibble: 2 × 6
expression min median itr/s…¹ mem_a…² gc/se…³
&lt;bch:expr&gt; &lt;bch:tm&gt; &lt;bch:tm&gt; &lt;dbl&gt; &lt;bch:b&gt; &lt;dbl&gt;
1 length(unique(test2)) == 1 483.8ms 512ms 1.93 332.3MB 1.93
2 all(test2 == test2[1]) 70.4ms 71ms 12.8 76.3MB 2.57
# … with abbreviated variable names ¹​`itr/sec`, ²​mem_alloc, ³​`gc/sec`</code></pre>
expression min median `itr/sec` mem_alloc `gc/sec`
&lt;bch:expr&gt; &lt;bch:t&gt; &lt;bch:t&gt; &lt;dbl&gt; &lt;bch:byt&gt; &lt;dbl&gt;
1 length(unique(test2)) … 342.2ms 390.6ms 2.46 332.3MB 2.46
2 all(test2 == test2[1]) 63.2ms 71.6ms 11.5 76.3MB 2.30</code></pre>
</div>
<p>This is also faster for character vectors:</p>
<div class="layout-chunk" data-layout="l-body">
Expand All @@ -2466,11 +2464,10 @@ <h2 id="check-if-a-vector-has-a-single-value">Check if a vector has a single val
<span><span class="op">)</span></span></code></pre>
</div>
<pre><code># A tibble: 2 × 6
expression min median itr/s…¹ mem_a…² gc/se…³
&lt;bch:expr&gt; &lt;bch:tm&gt; &lt;bch:tm&gt; &lt;dbl&gt; &lt;bch:b&gt; &lt;dbl&gt;
1 length(unique(test3)) == 1 449ms 474ms 2.10 332.3MB 2.10
2 all(test3 == test3[1]) 134ms 138ms 6.88 76.3MB 1.38
# … with abbreviated variable names ¹​`itr/sec`, ²​mem_alloc, ³​`gc/sec`</code></pre>
expression min median `itr/sec` mem_alloc `gc/sec`
&lt;bch:expr&gt; &lt;bch:t&gt; &lt;bch:&gt; &lt;dbl&gt; &lt;bch:byt&gt; &lt;dbl&gt;
1 length(unique(test3)) =… 287.8ms 326ms 3.00 332.3MB 3.00
2 all(test3 == test3[1]) 82.7ms 107ms 8.73 76.3MB 1.75</code></pre>
</div>
<h2 id="concatenate-columns">Concatenate columns</h2>
<p>Sometimes we need to concatenate columns, for example if we want to create a
Expand Down Expand Up @@ -2499,8 +2496,8 @@ <h2 id="concatenate-columns">Concatenate columns</h2>
<pre><code># A tibble: 2 × 6
expression min median `itr/sec` mem_alloc `gc/sec`
&lt;bch:expr&gt; &lt;bch:tm&gt; &lt;bch:tm&gt; &lt;dbl&gt; &lt;bch:byt&gt; &lt;dbl&gt;
1 apply 7.78s 7.78s 0.129 80.1MB 5.14
2 do.call 297.4ms 297.59ms 3.36 11.4MB 0 </code></pre>
1 apply 7.36s 7.36s 0.136 80.1MB 5.71
2 do.call 128.14ms 139.29ms 7.08 11.4MB 0 </code></pre>
</div>
<h2 id="giving-attributes-to-large-dataframes">Giving attributes to large dataframes</h2>
<p>This one comes from these <a href="https://stackoverflow.com/questions/74029805/why-does-adding-attributes-to-a-dataframe-take-longer-with-large-dataframes">StackOverflow question and answer</a>. Manipulating a dataframe can remove some attributes. For example, if I give an
Expand Down Expand Up @@ -2556,8 +2553,8 @@ <h2 id="giving-attributes-to-large-dataframes">Giving attributes to large datafr
<pre><code># A tibble: 2 × 6
expression min median `itr/sec` mem_alloc `gc/sec`
&lt;bch:expr&gt; &lt;bch:tm&gt; &lt;bch:tm&gt; &lt;dbl&gt; &lt;bch:byt&gt; &lt;dbl&gt;
1 old 87ms 92.3ms 10.8 38.2MB 2.70
2 new 88.5µs 95.3µs 9422. 24.4KB 6.80</code></pre>
1 old 68ms 82ms 12.9 38.2MB 4.29
2 new 52.8µs 80.5µs 11188. 24.4KB 8.77</code></pre>
</div>
<h2 id="find-empty-rows">Find empty rows</h2>
<p>It can be useful to remove empty rows, meaning rows containing only <code>NA</code> or <code>&quot;&quot;</code>.
Expand Down Expand Up @@ -2588,8 +2585,8 @@ <h2 id="find-empty-rows">Find empty rows</h2>
<pre><code># A tibble: 2 × 6
expression min median `itr/sec` mem_alloc `gc/sec`
&lt;bch:expr&gt; &lt;bch:tm&gt; &lt;bch:tm&gt; &lt;dbl&gt; &lt;bch:byt&gt; &lt;dbl&gt;
1 apply 2.8s 2.8s 0.357 112.9MB 3.22
2 rowSums 739.3ms 739.3ms 1.35 99.7MB 0 </code></pre>
1 apply 2.08s 2.08s 0.480 112.9MB 3.84
2 rowSums 709.59ms 709.59ms 1.41 99.7MB 0 </code></pre>
</div>
<h2 id="conclusion">Conclusion</h2>
<p>These were just a few tips I discovered. Maybe there are ways to make them even
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