How to summarise each column using dplyr package in R?
This recipe helps you summarise each column using dplyr package in R
Recipe Objective
Aggregation is one of the fundamental techniques in data manipulation that a data scientist should know. In R, we have dplyr package which is an add-on package most widely used to carry out data manipulation tasks. To carry out the task of aggregation, dplyr package provides us with group_by() function. We use summarise_each() and sumarise() function along with aggregation functions to summarise one or more than variable on the aggregated data by appplying functions like mean, min, max etc.
These functions take vectors as input and return a single numeric value after applying some in-built or user-defined functions on them.
Especifically summarise_each() function is used if we want to manipulate more than one variable by applying more than one function on each variable.
Syntax: summarise_each(x, funs(...) , ...)
Where:
- x = dataframe
- funs(...) = function to be applied on the variables specified after
- ... = variables to be manipulated
In this recipe, we will learn how to summarise each column using dplyr package in R.
Step 1: Loading the required library and Creating a DataFrame
Creating a STUDENT dataframe with Name and marks of two subjects in 3 Trimester exams.
# data manipulation
library(dplyr)
library(tidyverse)
STUDENT = data.frame(Name = c("Ram","Ram", "Ram", "Shyam", "Shyam", "Shyam", "Jessica", "Jessica", "Jessica"),
Science_Marks = c(55, 60, 65, 80, 70, 75, 45, 65, 70),
Math_Marks = c(70, 75, 73, 50, 53, 55, 65, 78, 75),
Trimester = c(1, 2, 3, 1, 2, 3, 1, 2, 3))
glimpse(STUDENT)
Rows: 9 Columns: 4 $ NameRam, Ram, Ram, Shyam, Shyam, Shyam, Jessica, Jessica,... $ Science_Marks 55, 60, 65, 80, 70, 75, 45, 65, 70 $ Math_Marks 70, 75, 73, 50, 53, 55, 65, 78, 75 $ Trimester 1, 2, 3, 1, 2, 3, 1, 2, 3
Step 2: Application of summarise_each Function
summarise_each(STUDENT, funs(min,max), Science_Marks, Math_Marks)
Query: To find the minimum and maximum marks for Science and Math subjects (Trimester 1, 2 and 3)
summarise_each(STUDENT, funs(min,max), Science_Marks, Math_Marks)
Science_Marks_min Math_Marks_min Science_Marks_max Math_Marks_max 45 50 80 78
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