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In the second part of our series we are going to meet three more googleVis charts. More specifically these charts are Area Chart, Stepped Area Chart and Combo Chart.

Read the examples below to understand the logic of what we are going to do and then test yous skills with the exercise set we prepared for you. Lets begin!

Answers to the exercises are available here.

Package & Data frame

As you already know, the first thing you have to do is install and load the googleVis package with:
```install.packages("googleVis") library(googleVis)```

Secondly we will create an experimental data frame which will be used for our charts’ plotting. You can create it with:
```df=data.frame(name=c("James", "Curry", "Harden"), Pts=c(20,23,34), Rbs=c(13,7,9))```

NOTE: The charts are created locally by your browser. In case they are not displayed at once press F5 to reload the page.

Area chart

It is quite simple to create an area chart with googleVis with:
```AreaC <- gvisBarChart(df) plot(AreaC)```

Exercise 1

Create a list named “AreaC” and pass to it the “df” data frame you just created as an area chart. HINT: Use `gvisAreaChart()`.

Exercise 2

Plot the area chart. HINT: Use `plot()`.

Stepped Area chart

Creating a stepped area chart is a little different than the area chart. You have to set the X and Y variables and also make it stacked in order to display the values correctly. Here is an example:
```SteppedAreaC <- gvisSteppedAreaChart(df, xvar="name", yvar=c("val1", "val2"), options=list(isStacked=TRUE)) plot(SteppedAreaC)```

Exercise 3

Create a list named “SteppedAreaC” and pass to it the “df” data frame you just created as a stepped area chart. You should also set the X variable as the players’ names and Y variable as their values. HINT: Use `gvisSteppedAreaChart()`, `xvar` and `yvar`.

Exercise 4

Plot the stepped area chart. HINT: Use `plot()`.

Learn more about using GoogleVis in the online course Mastering in Visualization with R programming. In this course you will learn how to:

• Work extensively with the GoogleVis package and its functionality
• Learn what visualizations exist for your specific use case
• And much more

Exercise 5

Now transform your stepped area chart to stacked to correct it and plot it.

Combo chart

The next chart we are going to meet is the combination of lines and bars chart known as combo chart. You can produce it like this:
```ComboC <- gvisComboChart(df, xvar="country", yvar=c("val1", "val2"), options=list(seriesType="bars", series='{1: {type:"line"}}')) plot(ComboC)```

Exercise 6

Create a list named “ComboC” and pass to it the “df” data frame you just created as a combo chart. You should also set the X variable as the players’ names and Y variable as their values. HINT: Use `gvisComboChart()`, `xvar` and `yvar`.

Exercise 7

Plot the chart. What kind of chart do you see? HINT: Use `plot()`.

In order to add the bars we have to set it as the example below.
```options=list(seriesType="bars", series='{1: {type:"line"}}')```

Exercise 8

Transform the chart you just created into a combo chart with bars and lines and plot it. HINT: Use `list()`.

Exercise 9

In the previous exercise “Pts” are represented by the bars and “Rbs” by the lines. Try to reverse them.

You can easily transform your combo chart into a column chart or a line chart just be setting `series='{1: {type:"line"}}'` to 2

Exercise 10

Transform the combo chart into a column chart and then into a line chart.