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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
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
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
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
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 log of each value 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 find the log if some columns are categorical.ExampleCreate the data frameLet’s create a data frame as shown below −Level
To find the cross product of two vectors in R by adding the elements, we can calculate outer product by using %o% operator.For example, if we have two vectors say x and y then cross product of these two vectors by adding the elements can be found by using the command given below −x%o%yCheck out the below examples to understand how it works.Example 1To find the cross product of two vectors in R by adding the elements, use the code given below −x1
By default, the position of X-axis is at the bottom and we know that it is always there in all software/programming tools. If we want to change the position of X-axis in base R plot then we can use axis function with pos argument. The pos argument will decide the position of the X-axis on Y-axis.Check out the Example mentioned below to understand how it can be done.ExampleTo change the position of X-axis in base R plot, use the following command −plot(1:10)OutputIf you execute the above given snippet, it generates the following Output −To create a point chart with X-axis ... Read More
To find the absolute maximum of each group in data.table object in R, we can follow the below steps −First of all, create a data.table object.Then, use summarise_each function of dplyr package along with which.max and abs function to find the absolute maximum of each group after grouping with group_by.Example 1Create the data.table objectLet’s create a data.table object as shown below −library(data.table) Class