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Get Standard Deviation of a Column in R dataframe
  • Last Updated : 07 Apr, 2021

In this article, we are going to find the standard deviation of a column in a dataframe in R Programming Language. 

To select the desired column of a dataframe $ is used.

Syntax:

dataframe$column_name

Formula for variance:



\frac{\Sigma(x_i-\overline{x})^2}{n-1}

where n is the total number of observations and x bar is the mean

Formula for standard deviation:

\sqrt{\frac{\Sigma(x_i-\mu)^2}{N}}

In the R programming language, for finding standard deviation on set of data, the method used is sd()

Syntax:

sd(data_values)

Where data-values are a vector input or data frame input.



Given below are some examples to help you understand this better

Example 1:

R




# data1 with vector of elements
data1=c(1,2,3,4,5)
  
# data2 with vector of elements
data2=c("sravan",'bobby','rohith','gnanu','ojaswi')
  
# give input to the data which is a dataframe
data=data.frame(a1=data1,a2=data2)
  
# finding standard deviation of dataframe
# column 1
print(sd(data$a1))

Output:

[1] 1.581139

Example 2:

R




# data1 with vector of elements
data1=c(1,2,3,4,5)
  
# data2 with vector of elements
data2=c(10,20,30,40,50)
  
# give input to the data which is a
# dataframe
data=data.frame(a1=data1,a2=data2)
  
# finding standard deviation of dataframe
# column 1
print(sd(data$a1))
  
# finding standard deviation of dataframe
# column 2
print(sd(data$a2))

Output:

[1] 1.581139

[1] 15.81139

Example 3:

R




# data1 with vector of elements (float
# values)
data1=c(1.0,2,3,4,5,8)
  
# data2 with vector of elements(float
# values)
data2=c(10,20.5,30.3,40,50,67.89)
  
# give input to the data which is a 
# dataframe
data=data.frame(a1=data1,a2=data2)
  
# finding standard deviation of dataframe 
# column 1
print(sd(data$a1))
  
# finding standard deviation of dataframe 
# column 2
print(sd(data$a2))

Output:

[1] 2.483277

[1] 20.86387




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