How to Extract a Column from R DataFrame to a List ?

In this article, we will discuss how to extract a column from a DataFrame to a List in R Programming Language.

Method 1: Converting all columns to list

In this method, we are going to create a vector with character (names) and integer(marks) type data and passing to the student dataframe. Similarly, we will pass these two vectors to the list and display them.

Syntax:

list(col1, col2,… ,col n)

Example:

R

# vector with names
names=c("bobby","pinkey","rohith","gnanu")

# vector with marks
marks=c(78,90,100,100)

# pass these vectors as inputs
# to the dataframe
student=data.frame(names,marks)

print(student)
print("----------------")

# pass those vectors to list
student_list=list(names,marks)
print(student_list)

Output:

Method 2: Using $

$ operator in R is used to extract a specific part of data or access a variable in a dataset. We can pass data frame column to a list by using $ operator. The columns to be selected are to be passed with dataframe name separated by $.

Syntax:

list(dataframe$column_name)

Example:

R

# vector with names
names=c("bobby","pinkey","rohith","gnanu")

# vector with marks
marks=c(78,90,100,100)

# pass these vectors as inputs
# to the dataframe
student=data.frame(names,marks)
print(student)
print("----------------")

# pass marks column  to list
print(list(student$marks))

Output:

We can extract more than one column using the same approach and then again pass it to the list() function.

Example:

R

# vector with names
names=c("bobby","pinkey","rohith","gnanu")

# vector with marks
marks=c(78,90,100,100)

# pass these vectors as inputs
# to the dataframe
student=data.frame(names,marks)
print(student)
print("----------------")

# pass all columns  to list
a=list(student$names,student$marks)
print(a)

Output:

Example :

R

# Creating a list
example_list <- list(P = 1:8,
                Q = letters[1:8],
                R = 5)
example_list

# Extracting the values of Q only using $ operator
example_list$Q

Output :

We can extract elements from a specific column in a list.