Week 01 - Introduction to R

# Week 01 - Introduction to R
## Basic functionalities
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### Danilo Freire
### 25th January 2019

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# Today's Agenda

* Installing R and RStudio

* Basic functions

* How to use `swirl()`

* Chapter 1 review

* Questions
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# Why R?

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# Why R?

# Why R?

# Why R?

# Why R?

# Why R?

# Why R?

# Why R?

# Why R?

# Installing R and RStudio

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# Installing R and RStudio

* <https://www.rstudio.com/products/rstudio/download/>

]

---

# Arithmetic Operations

```r
2 + 2
```

```
## [1] 4
```

```r
10 - 8
```

```
## [1] 2
```

```r
5^2
```

```
## [1] 25
```

```r
sqrt(81)
```

```
## [1] 9
```

```r
2/3
```

```
## [1] 0.6666667
```
---

# Objects

```r
x <- 5 # arrow (<-) is the assignment operator in R 
y <- 16
x + y
```

```
## [1] 21
```

```r
sqrt(x*y)
```

```
## [1] 8.944272
```
---

# Relational operations

```r
x > y
```

```
## [1] FALSE
```

```r
x <= 5
```

```
## [1] TRUE
```

```r
y == 16
```

```
## [1] TRUE
```

```r
x != 5
```

```
## [1] FALSE
```
---

# Vectors

```r
world.pop <- c(2525779, 3026003, 3691173, 4449049, 5320817, 6127700, 6916183)
pop.first <- c(2525779, 3026003, 3691173) 
pop.second <- c(4449049, 5320817, 6127700, 6916183)
pop.all <- c(pop.first, pop.second) 
pop.all
```

```
## [1] 2525779 3026003 3691173 4449049 5320817 6127700 6916183
```

```r
class <- "POLS 1600" # you can add characters too
class
```

```
## [1] "POLS 1600"
```
---

# Functions

```r
mean(world.pop) #function name, parentheses, object
```

```
## [1] 4579529
```

```r
min(world.pop)
```

```
## [1] 2525779
```

```r
max(world.pop)
```

```
## [1] 6916183
```

```r
median(world.pop)
```

```
## [1] 4449049
```

```r
summary(world.pop)
```

```
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
## 2525779 3358588 4449049 4579529 5724258 6916183
```
---

# Selecting observations

```r
world.pop[2]
```

```
## [1] 3026003
```

```r
world.pop[c(1,2)] # c() for combine. 
```

```
## [1] 2525779 3026003
```
---

# Data frames

```r
year <- seq(from = 1950, to = 2010, by = 10)
pop <- data.frame(year, world.pop) # add variables
summary(pop)
```

```
##       year        world.pop      
##  Min.   :1950   Min.   :2525779  
##  1st Qu.:1965   1st Qu.:3358588  
##  Median :1980   Median :4449049  
##  Mean   :1980   Mean   :4579529  
##  3rd Qu.:1995   3rd Qu.:5724258  
##  Max.   :2010   Max.   :6916183
```

```r
dim(pop) # row, column
```

```
## [1] 7 2
```

```r
pop$world.pop # access one column
```

```
## [1] 2525779 3026003 3691173 4449049 5320817 6127700 6916183
```
---

# Read data files

```r
*df <- read.csv("/Users/politicaltheory/Documents/github/pols1600/files/datasets/turnout.csv")
dim(df)
```

```
## [1] 14  9
```

```r
summary(df)
```

```
##       year           VEP              VAP             total       
##  Min.   :1980   Min.   :159635   Min.   :164445   Min.   : 64991  
##  1st Qu.:1986   1st Qu.:171192   1st Qu.:178930   1st Qu.: 73179  
##  Median :1993   Median :181140   Median :193018   Median : 89055  
##  Mean   :1993   Mean   :182640   Mean   :194226   Mean   : 89778  
##  3rd Qu.:2000   3rd Qu.:193353   3rd Qu.:209296   3rd Qu.:102370  
##  Max.   :2008   Max.   :213314   Max.   :230872   Max.   :131304  
##                                                                   
##       ANES           felons         noncit         overseas   
##  Min.   :47.00   Min.   : 802   Min.   : 5756   Min.   :1803  
##  1st Qu.:57.00   1st Qu.:1424   1st Qu.: 8592   1st Qu.:2236  
##  Median :70.50   Median :2312   Median :11972   Median :2458  
##  Mean   :65.79   Mean   :2177   Mean   :12229   Mean   :2746  
##  3rd Qu.:73.75   3rd Qu.:3042   3rd Qu.:15910   3rd Qu.:2937  
##  Max.   :78.00   Max.   :3168   Max.   :19392   Max.   :4972  
##                                                               
##     osvoters  
##  Min.   :263  
##  1st Qu.:263  
##  Median :263  
##  Mean   :263  
##  3rd Qu.:263  
##  Max.   :263  
##  NA's   :13
```
---

# Read data files

```r
str(df) # structure, quick way to visualise data
```

```
## 'data.frame':	14 obs. of  9 variables:
##  $ year    : int  1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 ...
##  $ VEP     : int  159635 160467 167702 170396 173579 176629 179656 182623 186347 190420 ...
##  $ VAP     : int  164445 166028 173995 177922 181955 186159 190778 195258 200016 205313 ...
##  $ total   : int  86515 67616 92653 64991 91595 67859 104405 75106 96263 72537 ...
##  $ ANES    : int  71 60 74 53 70 47 75 56 73 52 ...
##  $ felons  : int  802 960 1165 1367 1594 1901 2183 2441 2586 2920 ...
##  $ noncit  : int  5756 6641 7482 8362 9280 10239 11447 12497 13601 14988 ...
##  $ overseas: int  1803 1982 2361 2216 2257 2659 2418 2229 2499 2937 ...
##  $ osvoters: int  NA NA NA NA NA NA NA NA NA NA ...
```
---

# Install and load packages

```r
install.packages("swirl")

# Load packages
library("swirl")

# Install course on swirl. You have to do it just once.
install.packages("devtools")
install_course_github("kosukeimai", "qss-swirl")
swirl()
```
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# Questions?

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# Homework

* Install `swirl()` and Kosuke's course and go through modules `INTRO1` and `INTRO2`
]

```r
install.packages("swirl")

# Load packages
library("swirl")

# Install Kosuke's course on swirl. 
install.packages("devtools")
install_course_github("kosukeimai", "qss-swirl")
swirl() # type 1 and good luck :)
```

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# Have a great weekend!