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Articles on Trending Technologies
Technical articles with clear explanations and examples
How to create smooth density curves without filling densities in R?
The density curves can be created by using stat_density function of ggplot2 package but it fills the curve with density hence it becomes difficult to recognize the curves. We can remove these densities by using geom="line" inside the stat_density function so that only the density curves will be plotted.ExampleConsider the below data frame:> G Response df dfOutputG Response 1 C 1.0229016 2 C 1.0058160 3 B 0.8831558 4 B 0.7729167 5 C 0.9130468 6 D 0.8431893 7 B 1.5003581 8 A 0.9687335 9 B 1.1139661 10 A 0.9211660 11 A 1.1790619 12 D 0.6349671 13 A 1.2616918 14 A 1.6021078 ...
Read MoreHow to subset rows of an R data frame using grepl function?
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:> 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 B ...
Read MoreCount numbers having 0 as a digit in C++
We are provided a number N. The goal is to find the numbers that have 0 as digit and are in the range [1, N].We will do this by traversing numbers from 10 to N ( no need to check from 1 to 9 ) and for each number we will check each digit using a while loop. If any digit is found as zero increment count and move to next number otherwise reduce the number by 10 to check digits until number is >0.Let’s understand with examples.Input N=11Output Numbers from 1 to N with 0 as digit: 1Explanation Starting from i=10 to ...
Read MoreNumber of Connected Components in an Undirected Graph in C++
Suppose we have n nodes and they are labeled from 0 to n - 1 and a list of undirected edges, are also given, we have to define one function to find the number of connected components in an undirected graph.So, if the input is like n = 5 and edges = [[0, 1], [1, 2], [3, 4]], then the output will be 2To solve this, we will follow these steps −Define a function dfs(), this will take node, graph, an array called visited, if visited[node] is false, then −visited[node] := truefor initialize i := 0, when i < size ...
Read MoreHow to find the group-wise correlation coefficient in R?
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:> 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 1 ...
Read MoreCount numbers in a range that are divisible by all array elements in C++
We are provided two numbers START and END to define a range of numbers. And also an array of positive numbers Arr[]. The goal is to find all the numbers that are divisible by all elements of Arr[] and are in the range [START, END] .Method 1 ( Naive Approach )We will do this by traversing numbers from START to END and for each number we will check if the number is divisible by all elements of the array. If yes increment count.Method 2 ( check divisibility by LCM of array elements )We will find the LCM of all array ...
Read MoreMaximum Size Subarray Sum Equals k in C++
Suppose we have an array called nums and a target value k, we have to find the maximum length of a subarray that sums to k. If there is not present any, return 0 instead.So, if the input is like nums = [1, -1, 5, -2, 3], k = 3, then the output will be 4, as the subarray [1, - 1, 5, -2] sums to 3 and is the longest.To solve this, we will follow these steps −ret := 0Define one map mn := size of numstemp := 0, m[0] := -1for initialize i := 0, when i < ...
Read MoreHow to convert a matrix into a matrix with single column in R?
If we have a matrix then we might want to convert it to matrix with single column for some analytical purpose such as multiplying with a vector that has the length equal to the total number of elements as in the matrix. Thus, the matrix can be converted to a single column matrix by using matrix function itself but for this we would need to nullify the column names and row names.Example1> M1 M1Output [, 1] [, 2] [, 3] ...
Read MoreHow to find the cumulative sum but restarts it if a value is 1 in R?
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:> ID Ratings df1 df1Output ID Ratings 1 1 0 2 2 2 3 3 0 4 4 0 5 5 0 6 6 2 ...
Read MoreCount numbers in range 1 to N which are divisible by X but not by Y in C++
We are provided a number N. The goal is to find the numbers that are divisible by X and not by Y and are in the range [1, N].Let’s understand with examples.Input N=20 X=5 Y=20Output Numbers from 1 to N divisible by X not Y: 2Explanation Only 5 and 15 are divisible by 5 and not 10.Input N=20 X=4 Y=7Output Numbers from 1 to N divisible by X not Y: 5Explanation Numbers 4, 8, 12, 16 and 20 are divisible by 4 and not 7.Approach used in the below program is as followsWe take an integer N.Function divisibleXY(int x, int y, int n) returns a count ...
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