Programming Articles - Page 1433 of 3363

The ListFiles() method returns an array holding the objects (abstract paths) of all the files (and directories) in the path represented by the current (File) object.The File Filter interface is filter for the path names you can pass this as a parameter to the listFiles() method. This method filters the file names passed on the passed filter.To get the files in a folder implement a FileFilter which accepts only files and pass it as a parameter to the listFiles() method.Following is a screen shot of the contents of the ExampleDirectoryExampleimport java.io.File; import java.io.FileFilter; import java.io.IOException; public class Demo{    public ... Read More

The listFiles() method of the File class returns an array holding the objects (abstract paths) of all the files (and directories) in the path represented by the current (File) object.To read the contents of all the files in a folder into a single file −Create a file object by passing the required file path as a parameter.Read the contents of each file using Scanner or any other reader.Append the read contents into a StringBuffer.Write the StringBuffer contents into the required output file.Exampleimport java.io.DataOutputStream; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.util.Scanner; public class Test {    public static void main(String ... Read More

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.Example1 Live Demox1

The List() method of the File class returns a String array containing the names of all the files and directories in the path represented by the current (File) object.In order to search for a file you need to compare the name of each file in the directory to the name of the required file using the equals() method.ExampleLive Demoimport java.io.File; import java.util.Arrays; import java.util.Scanner; public class Example {    public static void main(String[] argv) throws Exception {       System.out.println("Enter the directory path: ");       Scanner sc = new Scanner(System.in);       String pathStr = sc.next(); ... Read More

The checking for duplicates in a data.table object can be easily done with the help of delta ($) operator that is used to access the columns and the duplicated function. For example, if a data.table object DT contains a column x then to check the duplicates in x, we can use the command duplicated(DT$x).Example1Loading data.table object and creating an object −library(data.table) set.seed(141) x

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

The String[] list(FilenameFilter filter) method of a File class returns a String array containing the names of all the files and directories in the path represented by the current (File) object. But the retuned array contains the filenames which are filtered based on the specified filter. The FilenameFilter is an interface in Java with a single method.accept(File dir, String name)To get the file names based on extensions implement this interface as such and pass its object to the above specified list() method of the file class.Assume we have a folder named ExampleDirectory in the directory D with 7 files and 2 directories ... Read More

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.Live Demoimport 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 More

When we create a plot using ggplot2, the axes labels are automatically generated for both the axes. We might want to use those axes labels for report writing or some other purpose, therefore, extraction of those labels for a plot created by using ggplot2 package can be found by using the ggplot_build function as shown in the below example but we need to save the plot in an object.Consider the below data frame −Example Live Demox

To change the defaults for ggplot2 geoms, we need to use update_geom_defaults function. If we want to change the shape of points for scatterplot, we can use the below syntax −update_geom_defaults("point",list(shape=”point_shape_number”))The point shape number ranges from 0 to 25. We can change that according to our need.Consider the below data frame −Example Live Demox