To find the frequency of unique values and missing values for each column in an R data frame, we can use apply function with table function and useNA argument set to always.For Example, if we have a data frame called df then we can find the frequency of unique values and missing values for each column in df by using the below mentioned command −apply(df,2,table,useNA="always")Example 1Following snippet creates a sample data frame −x1

To convert first letter into capital in single column data.table object in R, we can follow the below steps −First of all, create a data.table object with string column.Then, use sub function along with mutate function of dplyr package to convert first letter into capital in string column.ExampleCreate the data.table objectLet’s create a data.table object as shown below −library(data.table) Names

To find the row median of columns having same name in data.table object in R, we can follow the below steps −First of all, create a data.table with some columns having same name.Then, use tapply along with colnames and median function to find the row median of columns having same name.ExampleCreate the data.tableLet’s create a data.table as shown below −library(data.table) DT

To find the frequency of unique values for each column in an R data frame, we can use apply function with table function.For Example, if we have a data frame called df then we can find the frequency of unique values for each column in df by using the below mentioned command −apply(df,2,table)Example 1Following snippet creates a sample data frame −x1

To generate a repeated values column with each value in output selected randomly in R data frame, we can use replicate function. The replicate function will repeat the vector values up to the number of times we want and each value will be randomly selected. To understand how it works, check out the below examples.Example 1Using replicate function to create a data frame df with normal random variable column of size 25 −x

To find the index of values in data.table object column in R if they occur once, we can follow the below steps −First of all, create a data.table object.Then, use which function along with duplicated function and single square brackets for subsetting to find the index of values in a column if they occur once.Example 1Create the data.table objectLet’s create a data.table object as shown below −library(data.table) x

As of now it is not possible to create a vector of matrices in R. If we want to do it, we should prefer a list, hence we can create a list with matrices.For Example, if we have matrices say M1, M2, and M3 and we want to create a list of these matrices then we can use the below given command −list(M1,M2,M3)ExampleTo create a vector of matrices in R, use the following snippet −List

To find the exponent 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 exponent if some columns are categorical.ExampleCreate the data frameLet’s create a data frame as shown below −Level

To convert first letter into capital in R data frame column, we can follow the below steps −First of all, create a data frame with string column.Then, use sub function to convert first letter into capital in string column.ExampleCreate the data frameLet’s create a data frame as shown below −Names

To create a column of rounded values in data frames stored in R list, we can follow the below steps −First of all, create a list of data frames.Then, use lapply function to create a column of rounded valuesin data frames stored in the list.ExampleCreate the list of data framesUsing data.frame function to create data frames and list function to create the list of those data frames −df1