Showing posts with label MutableList. Show all posts
Showing posts with label MutableList. Show all posts

Count Occurrences in List item and String in KOTLIN

  9:13 PM            No comments

 



Here is some way to find out how to count list item from the list, only first char in list and many more;

1. Count first character with start particular char on list 

fun countOccurrencesOnlyFirstCharUsingCount() {
    val list = listOf("one", "two", "three", "four", "five", "six",
                        "seven", "eight", "nine", "ten")
    val char = 't'
    val count = list.count { it.startsWith(char) }
    println("$char => $count")
}

output:

/*
t => 3
*/

2. Count occurrence first all characters on list

fun countOccurrencesFirstCharUsingGroupingBy() {
    val list = listOf("one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten")
    val frequenciesByFirstChar = list.groupingBy { it.first() }.eachCount()
    println(frequenciesByFirstChar) // {o=1, t=3, f=2, s=2, e=1, n=1}
}

output:

/*
{o=1, t=3, f=2, s=2, e=1, n=1}
*/


3. Count occurrence of word in list by using groupingBy and eachCount

fun countOccurrencesUsingGroupingBy() {
    val list  = listOf("usa", "china","japan","usa", "canada","usa","canada", "japan", "india","japan")
    println(list.groupingBy { it }.eachCount())

}

output:

/*
{usa=3, china=1, japan=3, canada=2, india=1}
*/

4. Count occurrence of word in list by using  MutableMap and for loop

fun countOccurrencesUsingMutableMap() {
   val list  = listOf("usa", "china","japan","usa", "canada","usa","canada", "japan", "india","japan")
    val countMap : MutableMap<String, Int> = HashMap()
    for (item in list){
        var count = countMap[item]
        if (count == null) count = 0
         countMap[item] = count + 1
    }
    println(countMap)
}

output:

/*
{usa=3, china=1, canada=2, japan=3, india=1}
*/

5. Count occurrence of word in list by using distinct, Collections and, frequency

fun countOccurrencesUsingCollection() {
    val list:List<String> = listOf("usa", "china","japan","usa", "canada","usa","canada", "japan", "india","japan")
    for(i in list.distinct()){
        println( "$i => ${Collections.frequency( list, i)}")
    }
}

output:

/*
usa => 3
china => 1
japan => 3
canada => 2
india => 1
*/

6. Count occurrence of word in list without (expect) banned word or list   (.filterNot, groupingBy ,  eachCount)

with help fo HashSet.

fun countOccurrencesUsingGroupingByBannedItem() {
    val list  = listOf("usa", "china","japan","usa", "canada","usa","canada", "japan", "india","japan")

    val banned = setOf("china","india")
    var bannedSet = banned.toHashSet()

    val wordCount = list.filterNot { it in bannedSet }.groupingBy { it } .eachCount()
    println(wordCount)
}

output:

/*
{usa=3, japan=3, canada=2}
*/


HAPPY CODING :) 

Sorting Array, List, Custom Object and Dates in Kotlin

  10:47 PM            No comments

 Here is some sorting example in KOTLIN.

Sorting Array using ArrayOf

----------

fun sortedArrayOf() {
    val array1 = arrayOf(44,6,1,9,23,11,5,19,3)
    array1.sort()
    println("Sorted array : ${array1.contentToString()}")
}
//output
/*
Sorted array : [1, 3, 5, 6, 9, 11, 19, 23, 44]
 */

IntArray Sorting

----------

fun sortingByIntArray() {
    val intArray = intArrayOf(4, 3, 2, 1)
    intArray.sort()
    println(intArray.joinToString())
    // output : 1, 2, 3, 4
}

 Sorting Alphabetically String Array

---------

fun sortingByAlphabetically() {
    val stringArray = mutableListOf("ccc", "aab","aaa", "zzz", "bbb")
    val tempSortedList = stringArray.sortedWith(compareBy { it })  //it.first() is for first letter only
    println("Sorted by ascending: $tempSortedList")
    //output: Sorted by ascending: [aaa, aab, bbb, ccc, zzz]
}


Get the first element of String Array

---------

fun getFirstDataOfList() {
    val stringArray = mutableListOf("ccc", "aab","aaa", "zzz", "bbb")
    val firstElement = stringArray.first()
    println("First Element: $firstElement")
    //output : First Element: ccc
}

Sorting Date Ascending

---------

fun sortingByDates() {
    val dates = mutableListOf(
            Date(2020, 3, 8),
            Date(2022, 8, 16),
            Date(2020, 1, 30),
            Date(1999, 1, 5)
    )
//useing sortBy
    dates.sortBy { it.toString() }
    dates.forEach { println(it) }
    println(".........")
//using sortWith
    dates.sortWith(compareBy<Date> { it.year }.thenBy { it.month }.thenBy { it.day })
    dates.forEach { println(it) }
    //for descending: dates.reverse()
    println(".........")
//using sortedWith
    val sortedDates = dates.sortedWith(compareBy<Date> { it.year }.thenBy { it.month }.thenBy { it.day })
    sortedDates.forEach { println(it) }
    //use for descending .reversed()
}

data class Date(val year: Int, val month: Int, val day: Int)

//output
/*  
    Date(year=1999, month=1, day=5)
    Date(year=2020, month=1, day=30)
    Date(year=2020, month=3, day=8)
    Date(year=2022, month=8, day=16)
    .........
    Date(year=1999, month=1, day=5)
    Date(year=2020, month=1, day=30)
    Date(year=2020, month=3, day=8)
    Date(year=2022, month=8, day=16)
    .........
    Date(year=1999, month=1, day=5)
    Date(year=2020, month=1, day=30)
    Date(year=2020, month=3, day=8)
    Date(year=2022, month=8, day=16)
*/


Sorting Ascending array by adding manually 

---------

fun sortByAddingManually() {
    val stringList: MutableList<String> = ArrayList()
    stringList.add("ccc")
    stringList.add("aab")
    stringList.add("aaa")
    stringList.add("zzz")
    stringList.add("bbb")
    stringList.sortBy { it }
    stringList.forEach { println(it) }
}
//output
//aaa
//aab
//bbb
//ccc
//zzz


Sorting by custom object

---------------------------

fun sortedCustomObject() {
    val persons: MutableList<People> = ArrayList()
    persons.add(People("ABC", 61))
    persons.add(People("XZY", 30))
    persons.add(People("ABB",61))
    persons.add(People("XYZ",30))
    persons.add(People("ABZ",61))

    println(".....Sorted Overall Object.....")
    persons.sortBy { it.toString() }
    persons.forEach { println(it) }
    println(".....Sorted First Name and then Age.....")
    val sortedListName = persons.sortedWith(compareBy({ it.name }, { it.age }))
    sortedListName.forEach { println(it) }
    println(".....Sorted First Age and then Name.....")
    val sortedListAge = persons.sortedWith(compareBy({ it.age }, { it.name }))
    sortedListAge.forEach { println(it) }
    println(".....Sorted First Age and then Name...thenBy....")
    persons.sortedWith(compareBy<People> { it.name }.thenBy { it.age })
    persons.forEach { println(it) }
    println(".....using lambda...")
    persons.sortBy { person -> person.age}
    persons.forEach { println(it) }

}
data class People(val name:String, val age: Int)

//output
/*
    .....Sorted Overall Object.....
    People(name=ABB, age=61)
    People(name=ABC, age=61)
    People(name=ABZ, age=60)
    People(name=XYZ, age=30)
    People(name=XZY, age=30)
    .....Sorted First Name and then Age.....
    People(name=ABB, age=61)
    People(name=ABC, age=61)
    People(name=ABZ, age=60)
    People(name=XYZ, age=30)
    People(name=XZY, age=30)
    .....Sorted First Age and then Name.....
    People(name=XYZ, age=30)
    People(name=XZY, age=30)
    People(name=ABZ, age=60)
    People(name=ABB, age=61)
    People(name=ABC, age=61)
*/

More details:

https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/sorted.html

I will try to adding more frequently, please keep visiting this blog.





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