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Articles by Nizamuddin Siddiqui
Page 131 of 196
Convert a numeric column to binary factor based on a condition in R data frame
To convert a numeric column to binary factor based on a condition in R data frame, we can use factor function along with ifelse function.For Example, if we have a data frame called df that contains a numerical column say Num and we want to convert it to a binary factor if Num is less than 100 then it will be Minor otherwise Major then we can use the below given command −df$Num_Factor
Read MoreHow to standardize data.table object column by group in R?
To standardize data.table object column by group, we can use scale function and provide the grouping column with by function.For Example, if we have a data.table object called DT that contains two columns say G and Num where G is a grouping column and Num is a numerical column then we can standardize Num by column G by using the below given command −DT[,"Num":=as.vector(scale(Num)),by=G]Example 1Consider the below data.table object −library(data.table) Grp
Read MoreReplace each value in a column with the largest value based on a condition in R data frame.
Suppose we have three columns say X, Y, and Z in an R data frame called df and we want to replace values in columns X and Y with the same value if the values are greater than values in Z and if they are less than the values in Z then we can replace with Z values.Check out the below Examples to understand how it can be done.Example 1Following snippet creates a sample data frame −x1
Read MoreHow to randomly replace values in an R data frame column?
The random replacement values in an R data frame column can be done with the help of sample function along with nrow function and single square subsetting.For Example, if we have a data frame called df that contains a columns say X and we want to randomly replace 5 values in X with 1.5 then we can use the below given command −df$X[sample(nrow(df),5)]
Read MoreHow to multiply corresponding values from two data.table objects in R?
To multiply corresponding values from two data.table objects in R, we can follow the below steps −First of all, create two data.table objects.Then, use mapply function to multiply corresponding values from those two data.table objects.ExampleCreate the first data.table objectLet’s create a data.table object as shown below −library(data.table) x1
Read MoreR Programming how to display both axes' labels of a ggplot2 graph in italics?
To display both axes’ labels of a ggplot2 graph in italics in R, we can use theme function where we can set the face of axis.text.x and axis.text.y argument to italic.For Example, if we have a data frame called df that contains two columns say X and Y then we can create a scatterplot of X and Y with axes labels in italics by using the below mentioned command −ggplot(df, aes(X, Y))+geom_point()+theme(axis.text.x=element_text(face="italic"), axis.text.y=element_text(face="italic"))ExampleFollowing snippet creates a sample data frame −x
Read MoreHow to change the color of a particular bar using geom_bar in R?
To change the color of a particular bar using geom_bar in R, we can provide the count corresponding to the value for which we want to change the color inside aes function.For Example, if we have a data frame called df that contains two columns say V and F where V is categorical and F is for frequency and we want to change the color of frequency 10 in bar plot then we can use the below mentioned command −ggplot(df, aes(V, F))+geom_bar(aes(fill=..F..==10), stat="identity")ExampleFollowing snippet creates a sample data frame −x
Read MoreHow to add a value to a particular matrix element in R?
To add a value to a particular matrix element in R, we can use subsetting for the particular value with single square brackets.For Example, if we have a matrix called M and we want to add 10 to the fifth value in second column then can use the below mentioned command −M[5,2]
Read MoreHow to find the number of zeros in each column of an R data frame?
To find the number of zeros in each column of an R data frame, we can follow the below steps −First of all, create a data frame.Then, use colSums function to find the number of zeros in each column.Example 1Create the data frameLet’s create a data frame as shown below −x
Read MoreHow to multiply corresponding row values in a matrix with single row matrix in R?
To multiply row values in a matrix having multiple rows with single row matrix in R, we can follow the below steps −First of all, create a matrix with multiple rows and a matrix with single row.Then, use mapply function to multiply row values in those matrices.ExampleCreate the first matrixLet’s create a matrix as shown below −M1
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