#+SETUPFILE:   notes.org
#+TITLE:       R Notes
#+DATE:        2015-05-02
#+DESCRIPTION: Notes I find useful as I learn and experiment with R.
#+KEYWORDS:    learning, r, stats, programming
#+BABEL: :session *R* :cache yes :results output graphics :exports both :tangle yes

* Vectors
** c is for combine
#+BEGIN_SRC R
sentence <- c("this", "is", "a", "sentence")
sentence                                     # [1] "this" "is" "a" "sentence"
#+END_SRC
** First index is 1, not 0
#+BEGIN_SRC R
sentence[1] # "this"
#+END_SRC
** Overwriting
#+BEGIN_SRC R
sentence[4] <- "silly"
sentence               # [1] "this" "is" "a" "silly"
#+END_SRC
** Appending
#+BEGIN_SRC R
sentence[5] <- "example"
sentence                 # [1] "this" "is" "a" "silly" "example"
#+END_SRC
** Getting multiple elements
#+BEGIN_SRC R
sentence[c(1, 5)] # [1] "this" "example"
#+END_SRC
** Ranges
#+BEGIN_SRC R
sentence[4:5]                          # [1] "silly" "example"
sentence[4:5] <- c("cool", "language") # [1] "this" "is" "a" "cool" "language"
#+END_SRC
** Sequences
#+BEGIN_SRC R
5:9 == seq(5, 9) # [1] TRUE TRUE TRUE TRUE TRUE
#+END_SRC
*** With a step
#+BEGIN_SRC R
seq(2, 8, 2)     # [1] 2 4 6 8
#+END_SRC
** Named elements
#+BEGIN_SRC R
named <- 1:3
names(named) <- c("this", "that", "the other")
named                                          # this      that the other
                                               #    1         2         3
named["the other"] <- 42
named["the other"] == named[3]                 # T
named[3] == 42                                 # T
#+END_SRC
** Combining
#+BEGIN_SRC R :results output graphics :file public_html/img/barplot_01.png :width 320 :height 320
sails <- c(1:10,5:1,1:30,15:1,1:20,10:1)
barplot(sails)
#+END_SRC

#+RESULTS:
[[file:public_html/img/barplot_01.png]]

[[./img/barplot_01.png]]
** Basic arithmetic
#+BEGIN_SRC R
misfits <- c(1, 3, 8) # [1] 1 3 8
misfits + 10          # [1] 11 13 18
misfits - 10          # [1] -9 -7 -2
misfits * 10          # [1] 10 30 80
misfits / 10          # [1] 0.1 0.3 0.8
#+END_SRC

Sort of like Clojure's ~map~.

#+BEGIN_SRC clojure
(for [f [+ - * /]] (map #(f % 10) '(1 3 8)))
#+END_SRC

Keep in mind, it doesn't alter the original variable.

#+BEGIN_SRC R
misfits # [1] 1 3 8
#+END_SRC
** Scatter plots
#+BEGIN_SRC R
x <-
#+END_SRC
** na.rm
#+BEGIN_SRC R
a <- c(1, NA, 2, NA, 3) # [1] 1 NA 2 NA 3
sum(a)                  # [1] NA
sum(a, na.rm = TRUE)    # [1] 6
#+END_SRC
* Links
- [[https://github.com/yurrriq/notes/blob/master/R.org?raw=true][R.org source]]