To find the dot product of two matrices in R, we can use dot function of geometry package.For Example, if we have two matrices say matrix1 and matrix2 then we can use the dot product of these two matrices by using the below given command −dot(matrix1,matrix2)Example 1Following snippet creates a sample matrix −M1

To separate a first text value and the remaining text in R data frame column values, we can follow the below steps −First of all, create a data frame.Then, use str_split function from stringr package to separate first text value and the remaining text.ExampleCreate the data frameLet’s create a data frame as shown below −Names

To extract a particular level from factor column in an R data frame, we can use levels function with the number of the factor.For Example, if we have a data frame called df that contains a factor column say F then we can find the third level in F by using the below given command −levels(df$F)[2]Example 1Following snippet creates a sample data frame −Grp

To find the count of each category in a data.table object column in R, we can follow the below steps −First of all, create a data.table object.Then, use summarise function of dplyr package after grouping along with n.ExampleCreate the data.table objectLet’s create a data.table object as shown below −library(data.table) factor

When we create a general linear model for logistic regression model, we need to specify the distribution family as binomial. The error “NA/NaN/Inf” occurs when we do not specify the distribution family. Hence, family="binomial" needs to be used inside glm function while creating the logistic regression model.Example 1Following snippet creates a sample data frame −iv1

To check if a set is a subset of another set, we can use all function with %in% operator. For example, if we have two vectors say x and y and we want to check whether x is a subset of y then we can use the command given below −all(x %in% y)Check out the below given examples to understand how it works.Example 1To check if a set is a subset of another set in R, use the snippet given below −set_x1

To split a number into digits in R, we can use strsplit function by reading the number with as.character and then reading the output with as.numeric.For example, if we have a number stored into an object called X then we can split the number stored in X into digits by using the command as follows −as.numeric(strsplit(as.character(X),"")[[1]])Example 1To split a number into digits in R, use the snippet given below −x1

To round each value to two decimal places in columns if some columns are categorical in R data frame, we can follow the below steps −First of all, create a data frame.Then, use numcolwise function from plyr package to round each value to two decimal places in columns if some columns are categorical.ExampleCreate the data frameLet’s create a data frame as shown below −Level

A sequence vector is created by using the sequence of numbers such as 1 to 15, 21 to 51, 101 to 150, -5 to 10. The length of this type of vectors can be found only by using the length function.For example, if we have a sequence vector say X then the length of X can be found by using the command given below −length(X)Example 1To find the length of sequence vector in R, use the code given below −x1

To find the percentiles for multiple columns in R data frame, we can use apply function with quantile function and providing the quantile probabilities with probs argument.For Example, if we have a data frame called df that contains multiple columns and we want to find three percentiles 0.25, 0.70, 0.90 then we can use the command given below −apply(df[],2,quantile,probs=c(0.25,0.70,0.90))Example 1Following snippet creates a sample data frame −x1