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Addition of a column with consecutive might have different objectives such as getting the sequence of numbers, representing serial numbers, representing ids, identification of each row, or a variable. We can use the sequence starting from any number up to the number of rows if we know the number of rows for this purpose.Example1Consider the below data frame:Live Demo> x1 x2 df1 df1Output x1 x2 1 6.137898 5.203712 2 5.283467 5.057344 3 5.873749 4.907388 4 7.628762 5.012650 5 4.134700 4.988379 6 5.340686 4.684900 7 5.126999 4.821752 8 3.722762 4.974044 9 ... Read More
Suppose, we have two arrays like these −const meals = ["breakfast", "lunch", "dinner"]; const ingredients = [ ["eggs", "yogurt", "toast"], ["falafel", "mushrooms", "fries"], ["pasta", "cheese"] ];We are required to write a JavaScript function that takes in two such arrays and maps the subarrays in the second array to the corresponding strings of the first array.Therefore, the output for the above arrays should look like −const output = { "breakfast" : ["eggs", "yogurt", "toast"], "lunch": ["falafel", "mushrooms", "fries"], "dinner": ["pasta", "cheese"] };ExampleThe code for this will be −const meals = ["breakfast", "lunch", "dinner"]; const ingredients ... Read More
Sometimes we want to find the conditional cumulative sums and these conditions can be resetting the cumulative if a particular value occurs. For example, finding the cumulative sum of a variable frame but restarting the sum if 1 occurs. In R, we can do this with the help of with, ave and cumusum function as shown in the below examples.Example1Consider the below data frame:Live Demo> ID Ratings df1 df1Output ID Ratings 1 1 0 2 2 2 3 3 0 4 4 0 5 5 0 6 6 ... Read More
We are required to write a JavaScript function that takes in two arrays of the same length.Our function should then combine corresponding elements of the arrays, to form the corresponding subarray of the output array, and then finally return the output array.If the two arrays are −const arr1 = ['a', 'b', 'c']; const arr2 = [1, 2, 3];Then the output should be −const output = [ ['a', 1], ['b', 2], ['c', 3] ];ExampleThe code for this will be −const arr1 = ['a', 'b', 'c']; const arr2 = [1, 2, 3]; const combineCorresponding = (arr1 = [], arr2 ... Read More
If we have two continuous and one categorical column in an R data frame then we can find the correlation coefficient between continuous values for the categories in the categorical column. For this purpose, we can use by function and pass the cor function with the spearman method as shown in the below examples.Example1Consider the below data frame:Live Demo> x1 y1 z1 df1 df1Output x1 y1 z1 1 A 1.1155324 2 2 C 0.9801564 3 3 B 0.9116162 1 4 A 0.8406772 3 5 C 0.8009355 2 6 A 0.9331637 2 7 B 1.0642089 ... Read More
The grepl function in R search for matches to argument pattern within each element of a character vector or column of an R data frame. If we want to subset rows of an R data frame using grepl then subsetting with single-square brackets and grepl can be used by accessing the column that contains character values.Example1Consider the below data frame:Live Demo> x1 y1 z1 df1 df1Output x1 y1 z1 1 A 0.8833979 5 2 B 0.5400075 1 3 C 0.6923827 3 4 B 1.5069186 2 5 B 0.8190962 2 6 B 0.8296171 1 7 ... Read More
If we have a column that represent factor then we might want to find the mean of values in other column(s) for the factor levels. This is helpful in comparing the levels of the factor. In R, we can find the mean for such type of data by using aggregate function. Check out the below examples to understand how it can be done.Example1Consider the below data frame:Live Demo> x1 y1 df1 df1Output x1 y1 1 D 5.801197 2 B 3.432060 3 B 6.154168 4 A 5.466655 5 D 5.171689 6 C 5.175170 7 B 5.353469 8 D ... Read More
Suppose, we have a nested array like this −const arr = ['zero', ['one', 'two' , 'three', ['four', ['five', 'six', ['seven']]]]];We are required to write a JavaScript function that takes in a nested array. Our function should then return a string that contains all the array elements joined by a semicolon (';')Therefore, for the above array, the output should look like −const output = 'zero;one;two;three;four;five;six;seven;';ExampleThe code for this will be −const arr = ['zero', ['one', 'two' , 'three', ['four', ['five', 'six', ['seven']]]]]; const buildString = (arr = [], res = '') => { for(let i = 0; i < arr.length; ... Read More
Suppose, we have an array of objects like this −const arr = [ { id : "23", name : "Item 1", isActive : true}, { id : "25", name : "Item 2", isActive : false}, { id : "26", name : "Item 3", isActive : false}, { id : "30", name : "Item 4", isActive : true}, { id : "45", name : "Item 5", isActive : true} ];We are required to write a JavaScript function that takes in one such object and return an array of the value of "id" property of all those ... Read More