68 lines
1.6 KiB
Org Mode
68 lines
1.6 KiB
Org Mode
#+TITLE: Datatable package
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#+DATE: 2021-10-26
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#+OPTIONS: creator:nil timestamp:nil todo:nil num:nil
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#+PROPERTY: header-args:R :results output :session *Rc* :cmdline :tangle yes
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#+PROPERTY: header-args:R+ :exports both
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#+SETUPFILE: https://fniessen.github.io/org-html-themes/org/theme-readtheorg.setup
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#+HTML_HEAD: <style> #content{max-width:1800px;}</style>
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#+HTML_HEAD: <style> p{max-width:800px;}</style>
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#+HTML_HEAD: <style> li{max-width:800px;}</style>
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#+HTML_HEAD: <style> pre.src{background: #f5f5f5;color:black;}</style>
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#+HTML_HEAD: <style> .example{background: #fefefa;color:black;}</style>
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#+begin_export html
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<div id="subtitle" style="float: center; text-align: center;">
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<p>
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Org document with
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<a href="http://www.r-project.org/">R</a> code
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</p>
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<p>
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<a href="http://www.r-project.org/">
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<img src="http://www.r-project.org/Rlogo.jpg"/>
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</a>
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</p>
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</div>
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#+end_export
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#+begin_src R :exports code
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rm(list = ls())
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#+end_src
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** Querying data.table
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Sintaxis:
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* ~DT[i, j, by]~
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Subseting by "i" and "j"
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** Subset rows in "i"
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#+begin_src R
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dt1 <- flights[origin == "JFK" & month == 6L]
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dt1
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#+end_src
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Get the first two rows
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#+begin_src R
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flights[1:2]
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#+end_src
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#+RESULTS:
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: year month day dep_delay arr_delay carrier origin dest air_time distance
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: 1: 2014 1 1 14 13 AA JFK LAX 359 2475
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: 2: 2014 1 1 -3 13 AA JFK LAX 363 2475
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: hour
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: 1: 9
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: 2: 11
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Ordering results of querying
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#+begin_src R
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dt_filt <- flights[order(origin, -dest)]
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dt_filt
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#+end_src
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