The transform() Function In R – Modify Value Of A Data Frame

Don’t miss this article if you want to use the transform() function in R. Please read the entire article; you will get a lot of helpful information and can use this function efficiently.

Transform() in R

We can use the transform() function to modify data columns or add new columns in a data frame quickly and easily.

The syntax of transform():

transform(dataframe, val)

Parameters:

• dataframe: The data frame is used modified.
• val: The new value is modified for data frame.

Using transform() to modify column

If you want to know how to use the transform() function to modify a column, follow the code below:

First, we need a data frame example as follows:

dataFrame <- data.frame(names = c("Anastasia Schaefer", "Shyann Barrows",
    "Candida Prosacco", "Marcos Swift",
    "Kassandra Watsica", "Angie Botsford"),
  math = c(9, 8, 6, 7, 8, 9),
  physic = c(10, 9, 10, 8, 8, 7),
  chemistry = c(9, 8, 10, 7, 9, 8))

# View data frame
dataFrame

Output:

              names    math physic chemistry
1 Anastasia Schaefer    9     10         9
2     Shyann Barrows    8      9         8
3   Candida Prosacco    6     10        10
4       Marcos Swift    7      8         7
5  Kassandra Watsica    8      8         9
6     Angie Botsford    9      7         8

Then, we will modify math column by using transform() function.

dataFrame <- data.frame(names = c("Anastasia Schaefer", "Shyann Barrows",
    "Candida Prosacco", "Marcos Swift",
    "Kassandra Watsica", "Angie Botsford"),
  math = c(9, 8, 6, 7, 8, 9),
  physic = c(10, 9, 10, 8, 8, 7),
  chemistry = c(9, 8, 10, 7, 9, 8))

attach(dataFrame)

# Add math column by 10 and divide by 2
newdataFrame <- transform(dataFrame, math = (math + 10) / 2)

# View new data frame
newdataFrame

Output:

              names   math physic chemistry
1 Anastasia Schaefer  9.5     10         9
2     Shyann Barrows  9.0      9         8
3   Candida Prosacco  8.0     10        10
4       Marcos Swift  8.5      8         7
5  Kassandra Watsica  9.0      8         9
6     Angie Botsford  9.5      7         8

Using transform() to create a new column

We will create a new medium column to calculate the average score by taking (math + physic + chemistry) / 3. See the code below to understand more:

dataFrame <- data.frame(names = c("Anastasia Schaefer", "Shyann Barrows",
    "Candida Prosacco", "Marcos Swift",
    "Kassandra Watsica", "Angie Botsford"),
  math = c(9, 8, 6, 7, 8, 9),
  physic = c(10, 9, 10, 8, 8, 7),
  chemistry = c(9, 8, 10, 7, 9, 8))

attach(dataFrame)

# Create a medium column
newdataFrame <- transform(dataFrame, medium = round((math + physic + chemistry) / 3))

# View new data frame
newdataFrame

Output:

              names    math physic chemistry medium
1 Anastasia Schaefer    9     10         9      9
2     Shyann Barrows    8      9         8      8
3   Candida Prosacco    6     10        10      9
4       Marcos Swift    7      8         7      7
5  Kassandra Watsica    8      8         9      8
6     Angie Botsford    9      7         8      8

You can create many columns, for example:

dataFrame <- data.frame(names = c("Anastasia Schaefer", "Shyann Barrows",
    "Candida Prosacco", "Marcos Swift",
    "Kassandra Watsica", "Angie Botsford"),
  math = c(9, 8, 6, 7, 8, 9),
  physic = c(10, 9, 10, 8, 8, 7),
  chemistry = c(9, 8, 10, 7, 9, 8))

attach(dataFrame)

# Create many columns
newdataFrame <- transform(dataFrame, medium = round((math + physic + chemistry) / 3),
  english = c(9, 8, 6, 9, 6, 10))

# View new data frame
newdataFrame

Output:

              names    math physic chemistry medium english
1 Anastasia Schaefer    9     10         9      9       9
2     Shyann Barrows    8      9         8      8       8
3   Candida Prosacco    6     10        10      9       6
4       Marcos Swift    7      8         7      7       9
5  Kassandra Watsica    8      8         9      8       6
6     Angie Botsford    9      7         8      8      10

Summary

I hope this article has brought you a lot of helpful knowledge. If you have any questions, please leave a comment below. I will answer as possible. Thanks for reading!

Maybe you are interested:

• Names in R: How To Use The Names() Function in R?
• Spread() Function In R: How To Use spread() In R
• Round() function in R: How To Use Round Function In R

Scott Miller

Hi, guys! My name’s Scott Miller. My current job is a software developer and I have shared a lot of quality articles about Javascript, C, C++, C#, Python, PHP, R, Java programming languages. I’m hoping they can assist you.

Name of the university: HCMUS
Major: IT
Programming Languages: C, C++, Python, R, Java, JavaScript