DZone
Thanks for visiting DZone today,
Edit Profile
  • Manage Email Subscriptions
  • How to Post to DZone
  • Article Submission Guidelines
Sign Out View Profile
  • Post an Article
  • Manage My Drafts
Over 2 million developers have joined DZone.
Log In / Join
Refcards Trend Reports Events Over 2 million developers have joined DZone. Join Today! Thanks for visiting DZone today,
Edit Profile Manage Email Subscriptions Moderation Admin Console How to Post to DZone Article Submission Guidelines
View Profile
Sign Out
Refcards
Trend Reports
Events
Zones
Culture and Methodologies Agile Career Development Methodologies Team Management
Data Engineering AI/ML Big Data Data Databases IoT
Software Design and Architecture Cloud Architecture Containers Integration Microservices Performance Security
Coding Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Culture and Methodologies
Agile Career Development Methodologies Team Management
Data Engineering
AI/ML Big Data Data Databases IoT
Software Design and Architecture
Cloud Architecture Containers Integration Microservices Performance Security
Coding
Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance
Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
  1. DZone
  2. Data Engineering
  3. Databases
  4. R: Ordering Rows in a Data Frame by Multiple Columns

R: Ordering Rows in a Data Frame by Multiple Columns

Mark Needham user avatar by
Mark Needham
·
Jan. 25, 13 · Interview
Like (0)
Save
Tweet
Share
14.87K Views

Join the DZone community and get the full member experience.

Join For Free
In one of the assignments of Computing for Data Analysis we needed to sort a data frame based on the values in  two of the columns and then return the top value.

The initial data frame looked a bit like this:

> names <- c("paul", "mark", "dave", "will", "john")
> values <- c(1,4,1,2,1)
> smallData <- data.frame(name = names, value = values)
> smallData
  name value
1 paul     1
2 mark     4
3 dave     1
4 will     2
5 john     1

I want to be able to sort the data frame by value and name both in ascending order so the final result should look like this:

  name value
3 dave     1
5 john     1
1 paul     1
4 will     2
2 mark     4

To do that we can use the order function which will tell us the indices of the vector in sorted order.

e.g. in our case

> order(c(1,4,1,2,1))
[1] 1 3 5 4 2

If we pass a collection of indices to the extract operation it’ll reorder the rows. e.g.

> smallData[c(5,4,3,2,1),]
  name value
5 john     1
4 will     2
3 dave     1
2 mark     4
1 paul     1

In our case we wire everything together like this to sort by the second column (value):

> smallData[order(smallData[,2]),]
  name value
1 paul     1
3 dave     1
5 john     1
4 will     2
2 mark     4

It’s a reasonably small tweak to get it to sort first by the second column and then by the first (name) which is what we want:

> smallData[order(smallData[,2], smallData[,1]),]
  name value
3 dave     1
5 john     1
1 paul     1
4 will     2
2 mark     4

If we wanted to use the column names instead of indices we’d do the following:

> smallData[order(smallData$value, smallData$name),]
  name value
3 dave     1
5 john     1
1 paul     1
4 will     2
2 mark     4

We could also rewrite it using the with function if we want to reduce the code further:

> smallData[with(smallData, order(value, name)),]
  name value
3 dave     1
5 john     1
1 paul     1
4 will     2
2 mark     4

As I understand it, when we use with we put smallData into the environment and evaluate the second argument to with with respect to that so in this case it allows us to refer to the column names of smallData.

Column (database) R (programming language) Data (computing) Frame (networking) Row (database)

Published at DZone with permission of Mark Needham, DZone MVB. See the original article here.

Opinions expressed by DZone contributors are their own.

Popular on DZone

  • Key Considerations When Implementing Virtual Kubernetes Clusters
  • A Complete Guide to AngularJS Testing
  • How to Develop a Portrait Retouching Function
  • How To Use Terraform to Provision an AWS EC2 Instance

Comments

Partner Resources

X

ABOUT US

  • About DZone
  • Send feedback
  • Careers
  • Sitemap

ADVERTISE

  • Advertise with DZone

CONTRIBUTE ON DZONE

  • Article Submission Guidelines
  • Become a Contributor
  • Visit the Writers' Zone

LEGAL

  • Terms of Service
  • Privacy Policy

CONTACT US

  • 600 Park Offices Drive
  • Suite 300
  • Durham, NC 27709
  • support@dzone.com
  • +1 (919) 678-0300

Let's be friends: