Line Graph

## Introduction

Line charts are used to examine trend over time.

### Agenda

• build
• simple line chart
• grouped line chart
• map aesthetics to variables
• modify line
• color
• type
• size

## Case Study

### Introduction

We will use a data set related to GDP growth rate. You can download it from here. It contains GDP (Gross Domestic Product) growth data for the BRICS (Brazil, Russia, India, China, South Africa) for the years 2000 to 2005.

### Data

gdp

## Plot

### Example

ggplot(gdp, aes(year, india)) +
geom_line()

### Instructions

ggplot(gdp, aes(year, india)) +
geom_line()
ggplot(gdp, aes(year, india)) +
geom_line()

## Line Color

### Example

ggplot(gdp, aes(year, india)) +
geom_line(color = 'blue')

### Instructions

ggplot(gdp, aes(year, india)) +
geom_line(color = 'blue')
ggplot(gdp, aes(year, india)) +
geom_line(color = 'blue')

## Line Type - Part 1

• 0 : blank
• 1 : solid
• 2 : dashed
• 3 : dotted
• 4 : dotdash
• 5 : longdash
• 6 : twodash

### Example

ggplot(gdp, aes(year, india)) +
geom_line(linetype = 2)

### Example

ggplot(gdp, aes(year, india)) +
geom_line(linetype = 'dashed')

### Instructions

ggplot(gdp, aes(year, india)) +
geom_line(linetype = 'dashed')
ggplot(gdp, aes(year, india)) +
geom_line(linetype = 'dashed')

## Line Size

### Example

ggplot(gdp, aes(year, india)) +
geom_line(size = 2)

### Instructions

ggplot(gdp, aes(year, india)) +
geom_line(size = 2)
ggplot(gdp, aes(year, india)) +
geom_line(size = 2)

## Reshape Data

### Introduction

Now let us map the aesthetics to the variables. The data used in the above example cannot be used as we need a variable with country names. We will use gather() function from the tidyr package to reshape the data.

gdp2

## Grouped Line Chart

### Example

ggplot(gdp2, aes(year, gdp, group = country)) +
geom_line()

### Instructions

ggplot(gdp2, aes(year, gdp, group = country)) +
geom_line()
ggplot(gdp2, aes(year, gdp, group = country)) +
geom_line()

## Map Color

### Example

ggplot(gdp2, aes(year, gdp, group = country)) +
geom_line(aes(color = country))

### Instructions

ggplot(gdp2, aes(year, gdp, group = country)) +
geom_line(aes(color = country))
ggplot(gdp2, aes(year, gdp, group = country)) +
geom_line(aes(color = country))

## Map Line Type

### Example

ggplot(gdp2, aes(year, gdp, group = country)) +
geom_line(aes(linetype = country))

### Instructions

ggplot(gdp2, aes(year, gdp, group = country)) +
geom_line(aes(linetype = country))
ggplot(gdp2, aes(year, gdp, group = country)) +
geom_line(aes(linetype = country))

## Map Line Width

### Example

ggplot(gdp2, aes(year, gdp, group = country)) +
geom_line(aes(size = country))
## Warning: Using size for a discrete variable is not advised.

### Instructions

ggplot(gdp2, aes(year, gdp, group = country)) +
geom_line(aes(size = country))
ggplot(gdp2, aes(year, gdp, group = country)) +
geom_line(aes(size = country))