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The list elements of two lists cannot be added directly but we can do this addition by unlisting the elements. To do this, we would need to use lapply function. For example, if we have two lists defined as x and y then the sum of the elements in these lists can be calculated as follows:Examplelapply(seq_along(x), function(i) unlist(x[i])+unlist(y[i]))Example1Live Demo> x1 x1Output[[1]] [1] 0 3 0 1 2 0 1 0 1 3 3 0 0 0 1 1 0 1 0 1 1 0 2 0 0 6 1 2 1 1 1 1 2 1 1 0 0 [38] ... Read More
If a list has the same length of elements (not sub-elements) as the length of each vector for which we want to create the data frame then we first need to create the data frame of vectors then we can easily add the list into the data frame. But if we have a list and other vectors then data frame cannot be created as data.frame function will read each value of the list separately.ExampleLive Demo> df1 df1Output x y 1 6 1 2 8 1 3 6 2 4 8 1 5 5 1 6 3 1 7 6 1 ... Read More
A horizontal line in a histogram is not much useful but we might want to create it in some situations such as where we want to display a specific value on the Y-axis that helps us to differentiate in the density of frequencies above or below a certain value. To create a horizontal line in a histogram, we simply need to use abline function as shown in the below exampleExample> x hist(x) > abline(h=100)OutputExample> abline(h=100,col="blue")OutputExample> abline(h=100,col="blue",lwd=5)Output
To display the superscript in a base R plot, we would need to use expression function inside text function. For example, if we want to display X-square inside a blank plot in base R then we can use the below code:plot(1:10,type="n") text(2,2,expression(X^2))Example1> plot(1:10,type="n") > text(2,2,expression(X^2==4))Output:Example2> text(5,5,expression(X^5==Center))Output:Example3> text(9,9,expression(Squared^2))Output:
The column values of an R data frame can be easily extracted by subsetting with single square brackets but if we want to extract the column values that match a pattern then we need to use grepl function inside single square brackets, this will help us to match the pattern of the values in the data frame columns.ExampleConsider the below data frame:Live Demo> set.seed(271) > x1 x2 df1 df1Output x1 x2 1 A242 B71 2 A123 B71 3 A242 B81 4 A242 B87 5 A123 B71 6 A321 B71 7 ... Read More
To create a sphere, we can use spheres3d function of rgl package. The rgl package is specifically designed to create real-time interactive 3D plots. If we want to create a sphere then we need to pass the values for the three axes and the radius of the sphere. We can also change the color of the sphere by introducing color argument inside spheres3d function.Example1Loading rgl package and creating a sphere:> library(rgl) > spheres3d(x=1,y=1,z=1,radius=1)Output:Example2> spheres3d(0,0,0,radius=1,color="blue")Output:Example3> spheres3d(0,0,0,radius=1,color="red")Output:
Suppose, we have an array of objects like this −const arr = [ {"time":"18:00:00"}, {"time":"10:00:00"}, {"time":"16:30:00"} ];We are required to write a JavaScript function that takes in one such array and does the following −Extract the times from the json code: so: 18:00:00, 10:00:00, 16:30:00Convert the times to this: [18,0], [10,0], [16,30]Put it in an array.Return the final array.ExampleThe code for this will be −const arr = [ {"time":"18:00:00"}, {"time":"10:00:00"}, {"time":"16:30:00"} ]; const reduceArray = (arr = []) => { let res = []; res = arr.map(obj => { return obj['time'].split(':').slice(0, 2).map(el => { return +el; }); }); return res; }; console.log(reduceArray(arr));OutputAnd the output in the console will be −[ [ 18, 0 ], [ 10, 0 ], [ 16, 30 ] ]
Suppose, we have an object like this −const obj = { "part1": [{"id": 1, "a": 50}, {"id": 2, "a": 55}, {"id": 4, "a": 100}], "part2":[{"id": 1, "b": 40}, {"id": 3, "b": 45}, {"id": 4, "b": 110}] };We are required to write a JavaScript function that takes in one such object. The function should merge part1 and part2 of the object to form an array of objects like this −const output = [ {"id": 1, "a": 50, "b": 40}, {"id": 2, "a": 55}, {"id": 3, "b": 45}, {"id": 4, "a": 100, "b": 110} ];ExampleThe code ... Read More
We have an array that holds several objects named student, each object student has several properties, one of which is an array named grades −const arr = [ { name: "Student 1", grades: [ 65, 61, 67, 70 ] }, { name: "Student 2", grades: [ 50, 51, 53, 90 ] }, { name: "Student 3", grades: [ 0, 20, 40, 60 ] } ];We need to create a function that loops through the student's array ... Read More
Suppose, we have a nested array of numbers like this −const arr = [23, 6, [2, [6, 2, 1, 2], 2], 5, 2];We are required to write a program that should print the numbers (elements) of this array to the screen.The printing order of the numbers should according to the level upto which they are nested.Therefore, the output for the above input should look like this −23 6 2 6 2 1 2 2 5 2ExampleThe code for this will be − ... Read More