Chapter 1 Quick Start: Comandos Básicos

Acompanhe aqui alguns comandos básicos da linguagem.

O R é uma linguagem com algumas características que a tornam mais adequada à Análise de Dados que outras linguagens de propósito geral como C, Java etc.

  1. Interpretada
  2. Tolerante a falha
  3. Orientada à Coleções (Vetores)

1.1 Basics: variables and assign

# This is a comment :-)

# help
help(plot)
## starting httpd help server ... done
# variables and assign...

# number
x = 10
y <- 1
class(x)
## [1] "numeric"
class(y)
## [1] "numeric"
# prints
x
## [1] 10
print(y)
## [1] 1
# vectors
x = c(1,2,3)
y <- seq(1,10,0.5)
z = c(1:10)
nomes <- c('ana','cris','julia')
x
## [1] 1 2 3
y
##  [1]  1.0  1.5  2.0  2.5  3.0  3.5  4.0  4.5  5.0  5.5  6.0  6.5  7.0  7.5  8.0
## [16]  8.5  9.0  9.5 10.0
z
##  [1]  1  2  3  4  5  6  7  8  9 10
nomes
## [1] "ana"   "cris"  "julia"
# NA and Inf
x = c(1,2,3,NA,5,6,1/0,7,8,9,10)
x
##  [1]   1   2   3  NA   5   6 Inf   7   8   9  10

1.2 Basic statistics

# mean
x = c(1:3)
mean(x)
## [1] 2
min(x)
## [1] 1
max(x)
## [1] 3
sum(x)
## [1] 6
x = c(1,NA,3)
mean(x)
## [1] NA
x = c(1,NA,3)
mean(x, na.rm = TRUE)
## [1] 2
x = c(1,1/0,3)
x
## [1]   1 Inf   3
mean(x)
## [1] Inf
# quartil
x = c(1,2,3,4,5)
quantile(x) 
##   0%  25%  50%  75% 100% 
##    1    2    3    4    5
y = c(1,2,3,4)
quantile(x)
##   0%  25%  50%  75% 100% 
##    1    2    3    4    5
z = c(0:10)
z
##  [1]  0  1  2  3  4  5  6  7  8  9 10
quantile(z)
##   0%  25%  50%  75% 100% 
##  0.0  2.5  5.0  7.5 10.0
summary(x)
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##       1       2       3       3       4       5

1.3 Basic plots

x = c(1:10)
hist(x)

barplot(x)

x = c(1,2,3,1,1,2,0,1,1)
hist(x)

x = rnorm(100) # random normal distribution
boxplot(x)

hist(x)

x = rnorm(100)
y = rnorm(100)

barplot(x,y)

boxplot(x,y)

plot(x,y) # scatter plot!

x = c('a','b','c','a','d','a','b')
hist(table(x))

1.4 Basic data set input and dataframes

head(mtcars)
##                    mpg cyl disp  hp drat    wt  qsec vs am gear carb
## Mazda RX4         21.0   6  160 110 3.90 2.620 16.46  0  1    4    4
## Mazda RX4 Wag     21.0   6  160 110 3.90 2.875 17.02  0  1    4    4
## Datsun 710        22.8   4  108  93 3.85 2.320 18.61  1  1    4    1
## Hornet 4 Drive    21.4   6  258 110 3.08 3.215 19.44  1  0    3    1
## Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2
## Valiant           18.1   6  225 105 2.76 3.460 20.22  1  0    3    1
names(mtcars)
##  [1] "mpg"  "cyl"  "disp" "hp"   "drat" "wt"   "qsec" "vs"   "am"   "gear"
## [11] "carb"
nrow(mtcars)
## [1] 32
x = mtcars$mpg
hist(x)

summary(x)
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##   10.40   15.43   19.20   20.09   22.80   33.90
# Exercise: explore the following data sets
# ... http://stat.ethz.ch/R-manual/R-patched/library/datasets/html/00Index.html
names(quakes)
## [1] "lat"      "long"     "depth"    "mag"      "stations"
names(cars)
## [1] "speed" "dist"
names(iris)
## [1] "Sepal.Length" "Sepal.Width"  "Petal.Length" "Petal.Width"  "Species"