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Articles on Trending Technologies
Technical articles with clear explanations and examples
Encoding decimal to factorial and back in JavaScript
ProblemCoding decimal numbers with factorials is a way of writing out numbers in a base system that depends on factorials, rather than powers of numbers.In this system, the last digit is always 0 and is in base 0!. The digit before that is either 0 or 1 and is in base 1!. The digit before that is either 0, 1, or 2 and is in base 2!, etc. More generally, the nth-to-last digit is always 0, 1, 2, ..., n and is in base n!.We will need two functions. The first one will receive a decimal number and return a ...
Read MoreDifference between numbers and string numbers present in an array in JavaScript
ProblemWe are required to write a JavaScript function that takes in a mixed array of number and string representations of integers.Our function should add up okthe string integers and subtract this from the total of the non-string integers.ExampleFollowing is the code −const arr = [5, 2, '4', '7', '4', 2, 7, 9]; const integerDifference = (arr = []) => { let res = 0; for(let i = 0; i < arr.length; i++){ const el = arr[i]; if(typeof el === 'number'){ res += el; }else if(typeof el === 'string' && +el){ res -= (+el); }; }; return res; }; console.log(integerDifference(arr));OutputFollowing is the console output −10
Read MoreHow to find the row and column index for upper triangular matrix elements in R?
To find the row and column index for upper triangular matrix elements in R, we can follow the below steps −First of all, create a matrix.Then, use which function with upper.tri function to find the row and column index for upper triangular matrix elements.After, that attach the values corresponding to each index using cbind function.Create the matrixLet’s create a matrix as shown below −M
Read MoreHow to find the frequency of continuously repeated string values in an R data frame column?
To find the frequency of continuously repeated string values in an R data frame column, we can follow the below steps −First of all, create a data frame with a string column.Then, use sequence function and rleid function after converting the data frame into data.table object to find the frequency of continuously repeated string values in data frame column.Create the data frameLet's create a data frame as shown below −x
Read MoreHow to find the proportion using normal distribution in R?
To find the proportion using normal distribution in R, we can use pnorm function where we can provide the mean and standard deviation of population along with sample, also the tail position can be set by using lower.tail argument to TRUE or FALSE. Check out the below examples to understand how it can be done.Example 1Finding the proportion of values above 55 when sample mean is 50 and standard deviation is 8 −pnorm(55, mean=50, sd=8, lower.tail=FALSE)Output[1] 0.2659855Example 2Finding the proportion of values above 60 when sample mean is 50 and standard deviation is 8 −pnorm(60, mean=50, sd=8, lower.tail=FALSE)Output[1] 0.1056498Example 3Finding ...
Read MoreHow to check if a character column only contains alphabets in R data frame?
To check if a character column only contains alphabets in R data frame, we can follow the below steps −First of all, create a data frame with a character column.Then, use grepl function to check if all the values in the column contains only alphabets.Example 1Let's create a data frame as shown below −x
Read MoreReplacing vowels with their 1-based index in a string in JavaScript
ProblemWe are required to write a JavaScript function that takes in a string and replaces all occurrences of the vowels in the string with their index in the string (1-based).It means if the second letter of the string is a vowel, it should be replaced by 2.ExampleFollowing is the code −const str = 'cancotainsomevowels'; const replaceVowels = (str = '') => { const vowels = 'aeiou'; let res = ''; for(let i = 0; i < str.length; i++){ const el = str[i]; if(vowels.includes(el)){ res += (i ...
Read MoreHow to create a subset of an R data frame based on multiple columns?
To create a subset of an R data frame based on multiple columns, we can follow the below steps −First of all, create a data frame.Then, use single square brackets to subset the data frame based on multiple columns.Create the data frameLet's create a data frame as shown below −x1
Read MoreRetrieving n smallest numbers from an array in their original order in JavaScript
ProblemWe are required to write a JavaScript function that takes in an array of numbers arr, and a number n.Our function should retrieve the n smallest from the array arr without disturbing their relative order. It means they should not be arranged in increasing or decreasing order rather they should hold their original order.ExampleFollowing is the code −const arr = [6, 3, 4, 1, 2]; const num = 3; const smallestInOrder = (arr = [], num) => { if(arr.length < num){ return arr; }; const copy = arr.slice(); copy.sort((a, b) => a - ...
Read MoreGolang Program to Read the Contents of a File
pre.prettyprint{width:99%!important;} a.demo{top:12px!important; float:right!important;}To read the contents of a file, we can take following steps −We can create a file called test.txt.Clean-up using defer statement.Write the contents of string.Call ReadFile() method to read the file.ReadFile reads the file named by filename and returns the contents.Print the content of the file.Examplepackage main import ( "fmt" "io/ioutil" "log" "os" ) func CreateFile() { file, err := os.Create("test.txt") if err != nil { log.Fatalf("failed creating file: %s", err) } defer file.Close() _, err = file.WriteString("Welcome to Tutorials Point") if err != ...
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