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<h1 class="title toc-ignore">Hadley Wickham: Data Science in R</h1>
</div>
<div id="on-machine-learning" class="section level2">
<h2>On Machine Learning</h2>
<ul>
<li>If you’re not using data to make decisions you’re just not going to be successful <strong>machine learning is not a magic wand</strong></li>
</ul>
</div>
<div id="on-using-new-technologies" class="section level2">
<h2>On using new technologies</h2>
<ul>
<li>When do you decide to change to a new technology:</li>
<li>read a lot of blogs, such as hacker-news for up to date information</li>
<li>often hard to evaluate new technology on existing work until after you’ve invested the time to learn it</li>
</ul>
</div>
<div id="data-science-process" class="section level2">
<h2>Data Science Process</h2>
<ul>
<li>Import Data</li>
<li>Tidy</li>
<li>Transform</li>
<li>Model - scales but doesn’t surprise</li>
<li>Visualize - see surprises you might not expect, but doesn’t scale very well</li>
<li>Communicate the results to others</li>
</ul>
<div id="to-use-modern-data-anyalysis-you-have-to-learn-to-program" class="section level3">
<h3>TO USE MODERN DATA ANYALYSIS YOU HAVE TO LEARN TO PROGRAM</h3>
<div id="two-old-tensions-in-r-programming" class="section level4">
<h4>Two old tensions in R programming</h4>
<ul>
<li>It is not just a programming langue, it is also an interactive data exploration tool. This causes some “surprises”</li>
<li>There is tension between being conservative vs Utopian. Basic R is much more conservative, things change slowly.</li>
</ul>
</div>
</div>
</div>
<div id="principals-of-tidyverse" class="section level2">
<h2>Principals of tidyverse</h2>
<ol style="list-style-type: decimal">
<li>share data structures: Use a consistent format</li>
<li>compose simple/uniform pieces: use the pipe</li>
<li>embrace functional programming: don’t write for loops when you don’t have to</li>
<li>write for humans: be nice to your future self</li>
</ol>
<div id="data-structures" class="section level3">
<h3>Data Structures</h3>
<ul>
<li>not everything fits into the data frame structure, but most will</li>
<li>data frames fit almost all needs</li>
<li>sometimes you want a table like data frame that holds more complex structures, like saving models to a table with their RMSE values.</li>
<li>In these cases you can use a <em>TIBBLE</em></li>
</ul>
<p>What if you have a mix of structures: - IE. training data + test data -> mode -> predictions -> rmse - Not limited inside a data frame to not just storing numbers but also COMPLEX OBJECTS - use tibble to put model in a list form</p>
</div>
</div>
<div id="tibble" class="section level2">
<h2>Tibble</h2>
<ul>
<li>lazy</li>
<li>work better with list columns</li>
<li>can hold complex objects, like models or other data frames</li>
</ul>
</div>
<div id="compose-simpleuniform-pieces" class="section level2">
<h2>Compose simple/uniform pieces</h2>
<ul>
<li>use the pipe!!</li>
<li>pipe allows to write functions and arrange them in a way that is easy to understand</li>
<li>thinking about code explicitly as a form of communication</li>
<li>especially helpful so you don’t have to curse past you, always think about future you EX.</li>
</ul>
<pre><code>bop_on(
scoop_up(
hop_through(foo_foo, forest),
field_most
),
head
)
)</code></pre>
<p>is much more confusing then</p>
<pre><code>foo_foo %>%
hop_through(forest) %>%
scop_up(field_mouse) %>%
bop_on(head)
)</code></pre>
</div>
<div id="functional-programing" class="section level2">
<h2>Functional Programing</h2>
<ul>
<li>the first time you make a recipe it’s good have very explicit text</li>
<li>for loops emphasize on the nouns, when we usually care about the verbs</li>
</ul>
<pre class="r"><code>library(purrr)
map_dbl(mtcars, mean)</code></pre>
<pre><code>## mpg cyl disp hp drat wt
## 20.090625 6.187500 230.721875 146.687500 3.596563 3.217250
## qsec vs am gear carb
## 17.848750 0.437500 0.406250 3.687500 2.812500</code></pre>
<pre class="r"><code>map_dbl(mtcars, median)</code></pre>
<pre><code>## mpg cyl disp hp drat wt qsec vs am
## 19.200 6.000 196.300 123.000 3.695 3.325 17.710 0.000 0.000
## gear carb
## 4.000 2.000</code></pre>
<p>Other fun functional programming functions!</p>
<pre class="r"><code>invoke_map()
pwalk()</code></pre>
</div>
<div id="write-for-humans" class="section level2">
<h2>Write for Humans</h2>
<ul>
<li>data analysis should be a little bit fun<br />
</li>
<li>embrace exquisite language</li>
<li>humans are pack animals (use stickers, join clubs, meet people)</li>
<li>start with the book!</li>
</ul>
</div>
<div id="rule-of-thumb-you-should-never-copy-and-paste-code-more-than-twice" class="section level2">
<h2>Rule of thumb: You should never copy and paste code, more than twice</h2>
<ul>
<li>write it to a function</li>
<li>or use a loop of some kind</li>
</ul>
</div>
<p>Copyright © 2017 Erin Grand</p>
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