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Articles on Trending Technologies
Technical articles with clear explanations and examples
How to convert a column values to column names in R?
To convert a column values to column names, we can use dcast function of reshape2 package. For example, if we have a data frame called df that contains two columns say x and y, where x is categorical and y is numerical. Now if we want to convert the categories in x as column names then it can be done as dcast(df, y~x).Example1Consider the below data frame −> x1 x2 df1 df1Output x1 x2 1 B 4 2 A 2 3 A 5 4 C 3 5 A 7 6 A 4 7 ...
Read MoreFind n-th node in Postorder traversal of a Binary Tree in C++
In this problem, we are given a binary tree and an integer N. The task is to find the n-th node in Postorder traversal of a Binary Tree.A binary tree has a special condition that each node can have a maximum of two children.Traversal is a process to visit all the nodes of a tree and may print their values too.Let’s take an example to understand the problem, InputN = 6Output3ExplanationPost order traversal of tree − 4, 5, 2, 6, 7, 3, 1Solution ApproachThe idea is to use the post order traversal of the binary tree which is done by ...
Read MoreFrom and Into Traits In Rust Programming
From and Into are two traits that Rust provides us. They are internally linked.From TraitWe make use of From trait when we want to define a trait to how to create itself from any other type. It provides a very simple mechanism with which we can convert between several types.For example, we can easily convert str into a String.ExampleConsider the example shown below:fn main() { let my_str = "hello"; let my_string = String::from(my_str); println!("{}", my_string); }OutputhelloWe can even convert our own types.ExampleConsider the example shown below:use std::convert::From; #[derive(Debug)] struct Num { value: i64, } impl From ...
Read MoreHow to add a vector to each row of a matrix in R?
To add a vector to reach row of a matrix, we can use addition sign (+) and create the repetition of the vector up to the number of rows in the matrix. For example, if we have a matrix called M then a vector say v can be added to each row of M by using the command −M+rep(v, each=nrow(M))Example1Consider the below matrix and the vector −> M1 M1Output [, 1] [, 2] [1, ] 3 2 [2, ] 3 3 [3, ] 4 2 [4, ] 5 1 [5, ...
Read MoreHashMap in Rust Programming
HashMap is an important data structure, as it allows us to store data in key-value pairs. In Rust, HashMap stores values by key.HashMap keys can be Boolean, Integer, strings or any other data type that implements the Eq and Hash traits.HashMaps can grow in size, and when the space becomes too excessive, they can also shrink themselves.We can create a HashMap in multiple ways, we can use either HashMap::with_capacity(uint) or HashMap::new().Following are the methods that HashMaps support:insert()get()remove()iter()ExampleLet’s see an example where we build a HashMap and use all these operations stated above.Consider the example shown below.use std::collections::HashMap; fn call(number: ...
Read MoreHow to add suffix to column names in R?
To add suffix to column names in R, we can use paste function. For example, if we have a data frame called df that contains three columns say x, y, and z and we want to add a suffix to these columns say underscore1 (_1) then it can be done by using the commandcolnames(df) x y z df1 df1Output x y z 1 6 3 2 2 9 7 5 3 5 7 6 4 5 9 6 5 2 5 9 6 4 5 4 7 2 0 7 8 2 5 8 9 4 5 8 10 6 ...
Read MoreHow to find the length of columns for missing values in R?
The length of columns for missing values means the number of missing values in the data frame. This can be easily done with the help of colSums function where we will find the total number of NA values with is.na. For example, if we have a data frame called df that contains some missing values then the length of columns for missing values can be found by using the command colSums(is.na(df)).Example1Consider the below data frame −> x1 x2 x3 x4 df1 df1Output x1 x2 x3 x4 1 NA NA 2 2 2 NA NA NA 2 3 1 NA ...
Read MoreLoop Keyword in Rust Programming
Rust provides a loop keyword that allows us to run an infinite loop. The infinite loop indicated by the help of the loop keyword can be broken by the use of the break keyword. Also, we can exit an iteration and continue the infinite loop with the help of the continue keyword.ExampleConsider the example shown below −fn main() { let mut count = 0u32; println!("Infinite loop begins!!"); // Infinite loop loop { count += 1; if count == 4 { println!("four"); continue; ...
Read MoreHow to match a column in a data frame with a column in another data frame in R?
To match a column in a data frame with a column in another data frame, we can use match function. For example, if we have two data frames called df1 and df2 each having one similar column and the second having an extra column then the matching can be done for similar columns and a new column in the first data frame can be created based on that match and the second column the second data frame. Check out the below examples to understand how it works.Example1> df1 df1Output x1 1 2 2 2 3 1 4 ...
Read MoreMatch in Rust Programming
Rust provides us with a match keyword that can be used for pattern matching. It is similar to the switch statement in C, and the first arm that matches is evaluated.ExampleConsider the example shown below −fn main() { let number = 17; println!("Tell me about {}", number); match number { 1 => println!("One!") 2 | 3 | 5 | 7 | 11 => println!("A prime"), 13..=19 => println!("A teen"), _ => println!("Ain't special"), } }In the above example, we are trying to use a ...
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