Homework_07

Homework 7: Data Manipulation using the dplyr package

Question 1

data(iris)
class(iris)

## [1] "data.frame"

150 Observations and 5 Variables

Question 2

iris1 <- filter(iris, Species %in% c("virginica","versicolor"), Sepal.Length>6, Sepal.Width>2.5)

56 Observations and 5 variables

Question 3

iris2<-select(iris1, Species, Sepal.Length, Sepal.Width)

56 Observations and 3 Variables

Question 4

iris3 <- arrange(iris2,by=desc(Sepal.Length))
 head(iris3)         

##     Species Sepal.Length Sepal.Width
## 1 virginica          7.9         3.8
## 2 virginica          7.7         3.8
## 3 virginica          7.7         2.6
## 4 virginica          7.7         2.8
## 5 virginica          7.7         3.0
## 6 virginica          7.6         3.0

56 Observations and 3 Variables

Question 5

iris4<- mutate(iris3, Sepal.Area = Sepal.Length*Sepal.Width)

56 Observations and 4 Variables

Question 6

iris5<-summarize(iris4, meanSepal.Length = mean(Sepal.Length),meanSepal.Width = mean(Sepal.Width), sampleSizeIris4=n())
print(iris5)

##   meanSepal.Length meanSepal.Width sampleSizeIris4
## 1         6.698214        3.041071              56

1 Observation and 3 Variables

Question 7

iris6 <- iris4 %>%
  group_by(Species) %>%
  summarize(meanSepal.Length = mean(Sepal.Length),meanSepal.Width = mean(Sepal.Width), sampleSizeIris4=n())

2 Observations and 4 Variables

Question 8

iris6b <- iris %>%
  filter(Species %in% c("virginica","versicolor"), Sepal.Length>6, Sepal.Width>2.5) %>%
  select(Species, Sepal.Length, Sepal.Width) %>%
  arrange(by=desc(Sepal.Length)) %>%
  mutate(Sepal.Area = Sepal.Length*Sepal.Width) %>%
  group_by(Species) %>%
  summarize(meanSepal.Length = mean(Sepal.Length),meanSepal.Width = mean(Sepal.Width), sampleSizeIris4=n()) 

Yields the same output

Question 9

iris %>%
  pivot_longer(cols= 1:4,
               names_to = "Measure",
               values_to= "Value")

## # A tibble: 600 × 3
##    Species Measure      Value
##    <fct>   <chr>        <dbl>
##  1 setosa  Sepal.Length   5.1
##  2 setosa  Sepal.Width    3.5
##  3 setosa  Petal.Length   1.4
##  4 setosa  Petal.Width    0.2
##  5 setosa  Sepal.Length   4.9
##  6 setosa  Sepal.Width    3  
##  7 setosa  Petal.Length   1.4
##  8 setosa  Petal.Width    0.2
##  9 setosa  Sepal.Length   4.7
## 10 setosa  Sepal.Width    3.2
## # … with 590 more rows