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Programming Articles
Page 1095 of 2547
How to extract the factor levels from factor column in an R data frame?
To extract the factor levels from factor column, we can simply use levels function. For example, if we have a data frame called df that contains a factor column defined with x then the levels of factor levels in x can be extracted by using the command levels(df$x). This extraction is helpful if we have a large number of levels.Example1x2
Read MoreHow to create bar chart based on two groups in an R data frame?
To create a bar chart based on two groups, we can use geom_bar function of ggplot2 package with position argument that defines the position of the groups. For example, if we have a data frame called df that contains two categorical variable x1 and x2 and the one response variable y then the bar chart can be created by using the below command −ggplot(df,aes(x1,y,fill=x2))+geom_bar(position=position_dodge(),stat="identity")Examplelibrary(ggplot2) ggplot(df,aes(Age_Group,Y,fill=Gender))+geom_bar(position=position_dodge(),stat="identity")Output
Read MoreHow to split a Java String into tokens with StringTokenizer?
The hasMoreTokens() method is used to test if there are more tokens available from this tokenizer's string.Exampleimport java.util.*; public class StringTokenizerDemo { public static void main(String[] args) { // creating string tokenizer StringTokenizer st = new StringTokenizer("Come to learn"); // checking elements while (st.hasMoreElements()) { System.out.println("Next element : " + st.nextElement()); } } }OutputNext element : Come Next element : to Next element : learn
Read MoreHow to check if a String contains another String in a case insensitive manner in Java?
One way to do it to convert both strings to lower or upper case using toLowerCase() or toUpperCase() methods and test.Examplepublic class Sample { public static void main(String args[]){ String str = "Hello how are you welcome to Tutorialspoint"; String test = "tutorialspoint"; Boolean bool = str.toLowerCase().contains(test.toLowerCase()); System.out.println(bool); } }Outputtrue
Read MoreWrite a java program to tOGGLE each word in string?
You can change the cases of the letters of a word using toUpperCase() and toLowerCase() methods.Split each word in the string using the split() method, change the first letter of each word to lower case and remaining letters to upper case.Examplepublic class Sample{ public static void main(String args[]){ String sample = "Hello How are you"; String[] words = sample.split(" "); String result = ""; for(String word:words){ String firstSub = word.substring(0, 1); String secondSub = word.substring(1); result = result+firstSub.toLowerCase()+secondSub.toUpperCase()+" "; } System.out.println(result); } }OutputhELLO hOW aRE yOU
Read MoreCheck if a string contains a number using Java.
To find whether a given string contains a number, convert it to a character array and find whether each character in the array is a digit using the isDigit() method of the Character class.Examplepublic class ContainsExample { public static void main(String args[]){ String sample = "krishna64"; char[] chars = sample.toCharArray(); StringBuilder sb = new StringBuilder(); for(char c : chars){ if(Character.isDigit(c)){ sb.append(c); } } System.out.println(sb); } }Output64
Read MoreJava String toCharArray() method example.
The toCharArray() method of a String class converts this string to a character array.Exampleimport java.lang.*; public class StringDemo { public static void main(String[] args) { // converts String value to character array type value String str = " Java was developed by James Gosling"; char retval[] = str.toCharArray(); // displays the converted value System.out.println("Converted value to character array = "); System.out.println(retval); } }OutputConverted value to character array = Java was developed by James Gosling
Read MoreHow to test String is null or empty?
We can verify whether the given string is empty using the isEmpty() method of the String class. This method returns true only if length() is 0.Exampleimport java.lang.*; public class StringDemo { public static void main(String[] args) { String str = "tutorialspoint"; // prints length of string System.out.println("length of string = " + str.length()); // checks if the string is empty or not System.out.println("is this string empty? = " + str.isEmpty()); } }Outputlength of string = 14 is this string empty? = false
Read MoreHow to Split a String with Escaped Delimiters?
The split(String regex) method of the String class splits this string around matches of the given regular expression.Examplepublic class Sample{ public static void main(String args[]){ String s = "|A|BB||CCC|||"; String[] words = s.split("\|"); for (String string : words) { System.out.println(string); } } }OutputA BB CCC
Read MoreJava string case change sample code examples.
You can change the cases using the toUpperCase() and toLowerCase() methods of the String class.Examplepublic class Sample { public static void main(String args[]){ String str = "Hello how are you"; String strUpper = str.toUpperCase(); System.out.println("Lower to upper : "+strUpper); String strLower = str.toLowerCase(); System.out.println("Upper to lower : "+strLower); } }OutputLower to upper : HELLO HOW ARE YOU Upper to lower : hello how are you
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