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Data Manipulation and Transformation Tutorials

How to Perform Matrix Multiplication in R

  • R-PROGRAMMING
To perform matrix multiplication in R, you can use %*% operator. The following method shows how you can do it with syntax. Method: Using %*% Operator matrix1 %*% matrix2 The following example shows how perform multiplication of matrices in R. Let’s see how we can multiply matrices in R: # Define matrix A <- matrix(c(7,8,9,4),ncol=2) B <- matrix(c(1,2,3,4),ncol=2) # Multiply matrix m <- A%*%B # Print matrix print(m) Output: [,1] [,2] [1,] 25 57 [2,] 16 40 Here the output shows multiplication of matrices using %*% operator.
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How to Plot an Equation in R

  • R-PROGRAMMING
To plot equation in R, you can use curve() function or ggplot2 package. The following methods show how you can do it with syntax. Method 1: Use curve() Function curve(equation, from=-10, to=10, , xlab="x", ylab="y") Method 2: Use ggplot2 Package library(ggplot2) ggplot(data.frame(m=c(-10, 10)), aes(m=m)) + stat_function(fun=equation) The following examples show how to plot equation in R using two different ways. Using curve() Function Let’s see how we can use curve() function in R:
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How to Quickly Create Pivot Tables in R

  • R-PROGRAMMING
To create pivot tables in R, you can use group_by() and summarise() function from dplyr package. The following method shows how you can do it with syntax. Method 1: Use dplyr Package df %>% group_by(group1,group2) %>% summarize(sum = sum(values), mean = mean(values)) The following example shows how to create pivot table in R using dplyr package. Using dplyr Package Let’s see how we can use group_by() and summarise() function from dplyr package in R:
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How to Read Specific Rows from CSV File into R

  • R-PROGRAMMING
There are two different methods in R to read specific rows from CSV file into R. The following methods show how you can do it with syntax. Method 1: Using read.csv() with skip Argument df <- read.csv("data.csv",skip=n) Method 2: Select Rows Based on Condition library(sqldf) df <- read.csv.sql("data.csv", sql = "condition", eol = "\n") In above syntax read.csv.sql method is used from sqldf package.It import rows from CSV file based on provided sql condition.
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How to Rename Files in R

  • R-PROGRAMMING
To rename files in R, you can use file.rename() function. The following method shows how you can do it with syntax. Method 1: Use file.rename() Function file.rename(from='old_file_name.csv', to='new_file_name.csv') The following example shows how to renam file in R using file.rename() function. Using file.rename() Function Let’s see how we can use file.rename() function in R: # Rename one file file.rename(from='Machine1.csv', to='Data.csv') Output: [1] TRUE Here the output shows TRUE which means we successfully rename the file name.
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How to Reshape Data Between Wide and Long Format in R

  • R-PROGRAMMING
To reshape data between wide and long format in R, you can use pivot_wider() and pivot_longer() function from tidyr library. The following methods show how you can do it with syntax. Method 1: Use pivot_longer() Function library(tidyr) pivot_longer(df, cols = everything()) Method 2: Use pivot_wider() Function library(tidyr) pivot_wider(df, names_from=group, values_from=c(column1, column2)) The following examples show how to reshape data between wide and long format in R. Using pivot_longer() Function Let’s see how we ca reshape dataframe to long format using pivot_longer() function in R:
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How to Save R Output to Text File

  • R-PROGRAMMING
To save R output to text file, you can use sink() function or cat() function in R. The following methods show how you can do it with syntax. Method 1: Use sink() Function # Rredirecting output to a file sink("file.txt") # Save output in file print("output") # Close the file sink() Method 2: Use cat() Function cat("output",file = "file.txt") The following examples show how to save R output in text file using two different methods.
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How to Solve a System of Equations in R

  • R-PROGRAMMING
To solve a equation in R, you can use solve() function in R. This function takes two main arguments: the coefficients of the equations and the right-hand side values. The following method shows how you can do it with syntax. Method 1: Use solve() Function solve(coefficients, RHS_values) The following example shows how to use solve() function to solve equation in R. Using solve() Function Let’s see how we can use solve() function in R:
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How to Sort a Data Frame in R

  • R-PROGRAMMING
To sort a dataframe in R, you can use order() or arrange() function from dplyr package. The following methods show how you can do it with syntax. Method 1: Use order() Function # Sort dataframe in ascending order df[order(df$column1), ] # Sort dataframe in descending order df[order(-df$column1), ] Method 2: Use arrange() Function library(dplyr) # Sort in ascending order df %>% arrange(column1) # Sort in descending order df %>% arrange(desc(column1)) The following examples show how to sort dataframe in R using two different approach.
3 min Read 1

How to Sort a Table in R

  • R-PROGRAMMING
To sort table in R there are two methods in R. The following methods show how you can do it with syntax. Method 1: Use order() Function # Sort in ascending order order(x) # Sort in descending order order(x,decreasing=TRUE) Method 2: Use sort() Function # Sort in ascending order sort(x) # Sort in descending order sort(x,decreasing=TRUE) The following examples show how to use these function in R. Use order() Function to Sort Table in Ascending Order Let’s see how we can use order() function in R:
2 min Read 1

How to Sum Specific Columns in R

  • R-PROGRAMMING
To calculate sum of specific column of dataframe you can use rowSums() function in R. The following method shows how you can do it with syntax. Method 1: Use rowSums() Function rowSums(df[ , c(columns to sum)]) The following example shows how to use rowSums() function in R. Use rowSums() to Calculate Sum of Specific Columns Let’s see how we can calculate sum of specific column of data frame: # Create data frame df <- data.
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How to Transpose a Data Frame in R

  • R-PROGRAMMING
You can transpose dataframe in R using two different methods. The following methods show how you can do it with syntax. Method 1: Use t() Function t(df) Method 2: Use transpose() Function from data.table Package library(data.table) transpose(df) The following examples show how to use these function in R. Use t() Function Let’s see how we can use t() function to transpose the dataframe: # Create dataframe df <- data.frame(Start_date=as.Date(c("2000-05-21","1998-03-28","2001-01-19","2003-04-27","2004-11-26","2008-11-25")), Machine_name = c("Machine1","Machine2","Machine3","Machine4","Machine5","Machine6"), Value = c(108,120,135,95,98,105),Reading= c(110,97,91,89,80,85)) # Transpose dataframe transpose_df <- t(df) # Print transposed dataframe print(transpose_df) Output:
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