Programming Articles - Page 896 of 3366

To create a column of log(1+x) 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 log(1+x) in 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

A diagonal matrix is a type of square matrix that contains zero at non-diagonal elements starting from left-upper to right-bottom. To convert a vector into a diagonal matrix in R, we can use diag function along with matrix function and use ncol argument where we can put the number of columns equal to the number of values in the vector. Check out the Examples given below to understand how it can be done.Example 1Following snippet a sample list −V1

To multiply vector values in sequence with matrix columns in R, we can follow the below steps −First of all, create a matrix.Then, create a vector.After that, use t function for transpose and multiplication sign * to multiply vector values in sequence with matrix columns.ExampleCreate the data frameLet’s create a data frame as shown below −M

To convert list with varying number of elements into a data frame in R, we can use stri_list2matrix function of stringi package along with as.data.frame function.For Example, if we have a list called LIST that contains varying number of elements then we can convert it into a data frame by using the below mentioned command −as.data.frame(t(stri_list2matrix(LIST)))Example 1Following snippet creates a sample list −List1

To combine two rows in R matrix by addition, we can follow the below steps −First of all, create a matrix.Then, using plus sign (+) to add two rows and store the addition in one of the rows.After that, remove the row that is not required by subsetting with single square brackets.ExampleCreate the matrixLet’s create a matrix as shown below −M

To convert alphabets to numbers in data.table object in R, we can follow the below steps −First of all, create a data.table object.Then, use mutate_each function of dplyr package along with chartr function to convert alphabets to numbers.ExampleCreate the data.table objectLet’s create a data.table object as shown below −library(data.table) v1

To find the percentage of values that lie within a range in R data frame column, we can follow the below steps −First of all, create a data frame.Then, use sum function along with extreme values for range and length function to find the percentage of values that lie within that range.ExampleCreate the data frameLet’s create a data frame as shown below −Var

To find the frequency of each value in an R data frame, we can use table function along with unlist function.For Example, if we have a data frame called df and we want to find the frequency of each value in df then we can use the below command −table(unlist(df))Example 1Following snippet creates a sample data frame −x1

To find the mean of a column summarized by other column names and common values in those columns in data.table object in R, we can follow the below steps −First of all, create a data.table object.Then, melt the data.table object using melt function from reshape2 package.After that, use dcast function to find the mean of a column summarized by other column names and common values in those columns.ExampleCreate the data.table objectLet’s create a data.table object as shown below −library(data.table) ID

To find the total by year column in an R data frame, we can use aggregate function with sum function.For Example, if we have a data frame called df that contains a year colmn say Year and a numerical column say Demand then we can find the total Demand by Year with the help of command given below −aggregate(df["Demand"],by=df["Year"],sum)Example 1Following snippet creates a sample data frame −Year