Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
How to find the row standard deviation of columns having same name in data.table object in R?
To find the row standard deviation of columns having same name in data.table object in R, we can follow the below steps −
First of all, create a data.table object with some columns having same name.
Then, use tapply along with colnames and sd function to find the row standard deviation of columns having same name.
Example
Create the data.table object
Let’s create a data.table object as shown below −
library(data.table) DT<- data.table(x=rpois(25,5),y=rpois(25,1),x=rpois(25,4),y=rpois(25,10),check.names=FALSE) DT
Output
On executing, the above script generates the below output(this output will vary on your system due to randomization) −
x y x y
1: 3 2 2 6
2: 6 1 4 8
3: 6 1 2 8
4: 3 0 2 10
5: 2 1 1 14
6: 5 1 8 7
7: 3 2 6 10
8: 5 0 1 7
9: 5 0 4 10
10: 5 1 5 12
11: 6 1 3 13
12: 2 1 6 18
13: 1 0 6 10
14: 7 1 5 3
15: 11 0 3 15
16: 3 1 6 10
17: 4 0 3 2
18: 5 3 3 8
19: 8 2 4 15
20: 5 1 1 11
21: 10 0 4 10
22: 4 1 6 7
23: 7 0 6 10
24: 5 1 6 9
25: 6 1 5 5
x y x yFind the row standard deviation of columns having same name
Using tapply along with colnames and sd function to find the row standard deviation of columns having same name in data.table object DT −
library(data.table) DT<- data.table(x=rpois(25,5),y=rpois(25,1),x=rpois(25,4),y=rpois(25,10),check.names=FALSE) t(apply(DT,1, function(x) tapply(x,colnames(DT),sd)))
Output
x y [1,] 0.7071068 2.828427 [2,] 1.4142136 4.949747 [3,] 2.8284271 4.949747 [4,] 0.7071068 7.071068 [5,] 0.7071068 9.192388 [6,] 2.1213203 4.242641 [7,] 2.1213203 5.656854 [8,] 2.8284271 4.949747 [9,] 0.7071068 7.071068 [10,] 0.0000000 7.778175 [11,] 2.1213203 8.485281 [12,] 2.8284271 12.020815 [13,] 3.5355339 7.071068 [14,] 1.4142136 1.414214 [15,] 5.6568542 10.606602 [16,] 2.1213203 6.363961 [17,] 0.7071068 1.414214 [18,] 1.4142136 3.535534 [19,] 2.8284271 9.192388 [20,] 2.8284271 7.071068 [21,] 4.2426407 7.071068 [22,] 1.4142136 4.242641 [23,] 0.7071068 7.071068 [24,] 0.7071068 5.656854 [25,] 0.7071068 2.828427
Updated on: 12-Nov-2021
72 Views
Advertisements