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Server Side Programming Articles
Page 1159 of 2109
How to find the row mean for columns in an R data frame by ignoring missing values?
To find the row mean for columns by ignoring missing values, we would need to use rowMeans function with na.rm. For example, if we have a data frame called df that contains five columns and some of the values are missing then the row means will be calculated by using the command: rowMeans(df,na.rm=TRUE).Consider the below data frame −Examplex1
Read MoreHow to remove rows from an R data frame that contains at least one NaN?
The NA values and NaN values are very different in nature, therefore, removal of rows containing NA values is different from removal of rows containing NaN values. For example, if we have a data frame that has NaN values the rows will be removed by using the is.finite function as shown in the below examples.Consider the below data frame −Examplex1
Read MoreHow to add a row to a frame from another data frame in R?
Sometimes we want to add new data to original data frame in situations such as we need more data for analysis, looking for comparison between small size and large size data, or some data is missing in the original data and hence need more to be added from other data sets. One such thing would be adding a new to an existing data frame from another data frame. It can be done with the help of rbind function as shown in the below example.Consider the below data frames df1 and df2 −Examplex
Read MoreHow to create boxplot for list elements using ggplot2 in R?
If list elements are of equal size having numerical values then the boxplot for each element can be created by using ggplot2 but before creating the boxplot we would need to convert the list to a data frame. The conversion of list elements to a data frame will be done by unlisting of elements and creating two columns, one for categories and one for response variable. Check out the below example to understand how it works.Consider the below list −ExampleList
Read MoreHow to create Directories using the File utility methods in Java?
Since Java 7 the File.02s class was introduced this contains (static) methods that operate on files, directories, or other types of files.The createDirectory() method of the Files class accepts the path of the required directory and creates a new directory.ExampleFollowing Java example reads the path and name of the directory to be created, from the user, and creates it.import java.io.IOException; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; import java.util.Scanner; public class Test { public static void main(String args[]) throws IOException { System.out.println("Enter the path to create a directory: "); Scanner sc = new Scanner(System.in); ...
Read MoreHow to multiply only one column in an R data frame with a number?
To multiply only one column with a number, we can simply use the multiplication operator * but need to replace the original column with the new values. For example, if we have a data frame called df that contains three columns x1, x2, and x3, and we want to multiply the second column x2 with 2 then it can be done as df$x2
Read MoreHow to create a combination of pairs from a vector in R?
To create a combination of pairs, we can use the combn function. This function will be helpful to use the vector length and the value 2 that represents a pair to create the combinations. Although, this is enough but we can transpose the output to get a better−looking output.Example1x1
Read MoreHow to convert a super class variable into a sub class type in Java
Inheritance is a relation between two classes where one class inherits the properties of the other class. This relation can be defined using the extends keyword as −public class A extends B{}The class which inherits the properties is known as sub class or, child class and the class whose properties are inherited is super class or, parent class.In inheritance a copy of super class members is created in the sub class object. Therefore, using the sub class object you can access the members of the both classes.Converting a super class reference variable into a sub class typeYou can try to convert ...
Read MoreHow to add a new value to each element of list in R?
Suppose we have a list that contain two elements and we get a new value for both of these elements then the problem of adding those values to the original list arises. This can be done with the help of mapply function. We can append the new values in the original easily but a vector of the new values needs to be created first.Example1List1
Read MoreHow to create a large vector with repetitive elements of varying size in R?
To create a large vector of repetitive elements of varying size we can use the rep function along with the logical vector as an index. The logical vector that contains TRUE or FALSE will define the selection or omission of the values in the vector created with the help of rep function as shown in the below examples. If the vector created by using rep is larger than the logical vector then the logical vector will be recycled.Example1x1
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