Difference between revisions of "R/C2/Merging-and-Importing-Data/English"

Opening slide

Learning Objectives

• Use built-in functions for exploring a data frame
• Merge two data frames
• Import data in different formats in R

Pre-requisites

http://spoken-tutorial.org

• Data frames in R
• R script in RStudio
• How to set working directory in RStudio

If not, please locate the relevant tutorials on R on this website.

System Specifications

• Ubuntu Linux OS version 16.04
• R version 3.4.4
• RStudio version 1.1.456

Install R version 3.2.0 or higher.

Download files

• five data frames in different formats and
• a script file myDataSet.R.

Please download these files from the Code files link of this tutorial.

Highlight data frames and myDataSet.R in the folder myProject

And moved them to DataMerging folder in myProject folder on the Desktop.

I have also set this folder as my Working Directory.

Point to myDataSet.R in Rstudio

For this, click on the script myDataSet.R.

Script myDataSet.R opens in RStudio.

Highlight captaincyOne in the Source window

For all the built-in functions used in this tutorial, please refer to the Additional Material.

summary(captaincyOne)

Highlight Source button

Save the script and run the current line by pressing Ctrl+Enter keys simultaneously.

Statistical parameters for each column of captaincyOne are shown on the Console.

Press Enter at the end of every command.

class(captaincyOne)

Save the script and run the current line.

typeof(captaincyOne)

Save the script and run the current line.

help(typeof)

For this, we will use head function.

head(captaincyOne, 2)

Save the script and run the current line.

For this, we will use the tail function.

tail(captaincyOne, 2)

Save the script and run the current line.

This function is used to display the structure of an R object.

str(captaincyOne)

Save the script and run the current line.

Merging data frames

• It makes data more available.
• It helps in improving data quality.
• Combining similar data also reduces data complexity.

Highlight CaptaincyData.csv and CaptaincyData2.csv under Files tab

captaincyTwo <- read.csv("CaptaincyData2.csv")

In the Source window, type the following command and press Enter.

View(captaincyTwo)

Save the script and run the last two lines.

Highlight the column drawn in captaincyTwo

However, it has different information about them like the number of matches drawn.

For this, we use merge function.

captaincyOne <- merge(captaincyOne, captaincyTwo, by = "names")

Here, it is names.

View(captaincyOne)

Save the script and run these two lines.

Highlight the tabs captaincyOne and captaincyTwo

# Importing data in different formats

In the Source window, type # hash space Importing data in different formats.

For that, we need to install XML package.

Make sure that you are connected to Internet.

Information on how to install this package, is provided in the Additional Material.

Click in the Console window

Hence, I will proceed for installing XML package now.

install.packages("XML")

Highlight the red dot in the Console window

Now, type XML inside double quotes and in parentheses.

Press Enter.

We will wait until R installs the package.

library(XML)

Now, at the top of the script myDataSet.R, type library and XML in parentheses.

Save the script and run this line.

Point to the comment.

xmldata <- xmlToDataFrame("CaptaincyData.xml")

Type the following command and press Enter.

View(xmldata )

Save the script and run these two lines.

txtdata <- read.table(“CaptaincyData.txt”)

[RStudio]

View(txtdata)

Save the script and run these two lines.

I am resizing the Source window.

We will import the Excel file CaptaincyData.xlsx using this method.

Please ensure that you have packages like readxl and Rcpp installed in your system.

Highlight From Excel option

From the drop-down menu, select From Excel.

We will select a file on our computer.

This folder is in myProject folder on the Desktop.

Click Open to load this file.

Summary

• Use built-in functions for exploring a data frame
• Merge two data frames
• Import data in different formats in R

Assignment

• Using built-in dataset iris, implement all the functions we have learnt in this tutorial.

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Acknowledgement

Thank You

This is Sudhakar Kumar from IIT Bombay signing off. Thanks for watching.