Home > Articles

  • Print
  • + Share This
This chapter is from the book

12.4 tidyr in Action: Exploring Educational Statistics

This section uses a real data set to demonstrate how reshaping your data with tidyr is an integral part of the data exploration process. The data in this example was downloaded from the World Bank Data Explorer,2 which is a data collection of hundreds of indicators (measures) of different economic and social development factors. In particular, this example considers educational indicators3 that capture a relevant signal of a country’s level of (or investment in) education—for example, government expenditure on education, literacy rates, school enrollment rates, and dozens of other measures of educational attainment. The imperfections of this data set (unnecessary rows at the top of the .csv file, a substantial amount of missing data, long column names with special characters) are representative of the challenges involved in working with real data sets. All graphics in this section were built using the ggplot2 package, which is described in Chapter 16. The complete code for this analysis is also available online in the book’s code repository.4

After having downloaded the data, you will need to load it into your R environment:

# Load data, skipping the unnecessary first 4 rows
wb_data <- read.csv(
  stringsAsFactors = F,
  skip = 4

When you first load the data, each observation (row) represents an indicator for a country, with features (columns) that are the values of that indicator in a given year (see Figure 12.3). Notice that many values, particularly for earlier years, are missing (NA). Also, because R does not allow column names to be numbers, the read.csv() function has prepended an X to each column name (which is just a number in the raw .csv file).


FIGURE 12.3 Untransformed World Bank educational data used in Section 12.4.

While in terms of the indicator this data is in long format, in terms of the indicator and year the data is in wide format—a single column contains all the values for a single year. This structure allows you to make comparisons between years for the indicators by filtering for the indicator of interest. For example, you could compare each country’s educational expenditure in 1990 to its expenditure in 2014 as follows:

# Visually compare expenditures for 1990 and 2014
# Begin by filtering the rows for the indicator of interest
indicator <- "Government expenditure on education, total (% of GDP)"
expenditure_plot_data <- wb_data %>%
  filter(Indicator.Name == indicator)
# Plot the expenditure in 1990 against 2014 using the `ggplot2` package
# See Chapter 16 for details
expenditure_chart <- ggplot(data = expenditure_plot_data) +
    mapping = aes(x = X1990 / 100, y = X2014 / 100, label = Country.Code)
  ) +
  scale_x_continuous(labels = percent) +
  scale_y_continuous(labels = percent) +
  labs(title = indicator, x = "Expenditure 1990", y = "Expenditure 2014")

Figure 12.4 shows that the expenditure (relative to gross domestic product) is fairly correlated between the two time points: countries that spent more in 1990 also spent more in 2014 (specifically, the correlation—calculated in R using the cor() function—is .64).


Figure 12.4 A comparison of each country’s education expenditures in 1990 and 2014.

However, if you want to extend your analysis to visually compare how the expenditure across all years varies for a given country, you would need to reshape the data. Instead of having each observation be an indicator for a country, you want each observation to be an indicator for a country for a year—thereby having all of the values for all of the years in a single column and making the data long(er) format.

To do this, you can gather() the year columns together:

# Reshape the data to create a new column for the `year`
long_year_data <- wb_data %>%
    key = year, # `year` will be the new key column
    value = value, # `value` will be the new value column
    X1960:X # all columns between `X1960` and `X` will be gathered

As shown in Figure 12.5, this gather() statement creates a year column, so each observation (row) represents the value of an indicator in a particular country in a given year. The expenditure for each year is stored in the value column created (coincidentally, this column is given the name "value").


FIGURE 12.5 Reshaped educational data (long format by year). This structure allows you to more easily create visualizations across multiple years.

This structure will now allow you to compare fluctuations in an indicator’s value over time (across all years):

# Filter the rows for the indicator and country of interest
indicator <- "Government expenditure on education, total (% of GDP)"
spain_plot_data <- long_year_data %>%
    Indicator.Name == indicator,
    Country.Code == "ESP" # Spain
  ) %>%
  mutate(year = as.numeric(substr(year, 2, 5))) # remove "X" before each year
# Show the educational expenditure over time
chart_title <- paste(indicator, " in Spain")
spain_chart <- ggplot(data = spain_plot_data) +
  geom_line(mapping = aes(x = year, y = value / 100)) +
  scale_y_continuous(labels = percent) +
  labs(title = chart_title, x = "Year", y = "Percent of GDP Expenditure")

The resulting chart, shown in Figure 12.6, uses the available data to show a timeline of the fluctuations in government expenditures on education in Spain. This produces a more complete picture of the history of educational investment, and draws attention to major changes as well as the absence of data in particular years.


Figure 12.6 Education expenditures over time in Spain.

You may also want to compare two indicators to each other. For example, you may want to assess the relationship between each country’s literacy rate (a first indicator) and its unemployment rate (a second indicator). To do this, you would need to reshape the data again so that each observation is a particular country and each column is an indicator. Since indicators are currently in one column, you need to spread them out using the spread() function:

# Reshape the data to create columns for each indicator
wide_data <- long_year_data %>%
  select(-Indicator.Code) %>% # do not include the `Indicator.Code` column
    key = Indicator.Name, # new column names are `Indicator.Name` values
    value = value # populate new columns with values from `value`

This wide format data shape allows for comparisons between two different indicators. For example, you can explore the relationship between female unemployment and female literacy rates, as shown in Figure 12.7.

# Prepare data and filter for year of interest
x_var <- "Literacy rate, adult female (% of females ages 15 and above)"
y_var <- "Unemployment, female (% of female labor force) (modeled
  ILO estimate)"
lit_plot_data <- wide_data %>%
    lit_percent_2014 = wide_data[, x_var] / 100,
    employ_percent_2014 = wide_data[, y_var] / 100
  ) %>%
  filter(year == "X2014")
# Show the literacy vs. employment rates
lit_chart <- ggplot(data = lit_plot_data) +
  geom_point(mapping = aes(x = lit_percent_2014, y = employ_percent_2014)) +
  scale_x_continuous(labels = percent) +
  scale_y_continuous(labels = percent) +
    x = x_var,
    y = "Unemployment, female (% of female labor force)",
    title = "Female Literacy Rate versus Female Unemployment Rate"

Figure 12.7 Female literacy rate versus unemployment rate in 2014.

Each comparison in this analysis—between two time points, over a full time-series, and between indicators—required a different representation of the data set. Mastering use of the tidyr functions will allow you to quickly transform the shape of your data set, allowing for rapid and effective data analysis. For practice reshaping data with the tidyr package, see the set of accompanying book exercises.5

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020