Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
Server Side Programming Articles
Page 1071 of 2109
How to wrap python object in C/C++?
To wrap existing C or C++ functionality in Python, there are number of options available, which are: Manual wrapping using PyMethodDef and Py_InitModule, SWIG, Pyrex, ctypes, SIP, Boost.Python, and pybind1. Using the SWIG Module Let’s take a C function and then tune it to python using SWIG. The SWIG stands for “Simple Wrapper Interface Generator”, and it is capable of wrapping C in a large variety of languages like python, PHP, TCL etc. Example Consider simple factorial function fact() in example.c file. /* File : example.c */ #include // calculate factorial int fact(int n) { ...
Read MoreHow to replace blanks in a vector with the previous element in R?
Filling of blanks is not an easy task in data analysis, especially if the vector contains numerical or integer values. Suppose we have a vector x that contains 1, , 2, 3, 4, 5 and we want to put 1 in place of blank after first value then cummax function along with seq_along function can be used as x[cummax(seq_along(x)*(x!=""))].Example1x1
Read MoreHow to create a vector with all dates in a particular year in R?
We know that some years are leap years and some are normal years. The leap years have 366 days and the normal years have 365 days. To create a vector with all dates in a particular year we can use first date and the last date of the year by reading them with as.Date and creating a sequence with seq function. Check out the below examples to understand how it is done.Example1Creating a vector with dates in year 2020 −seq(as.Date("2020-01-01"), as.Date("2020-12-31"), by="1 day")Output[1] "2020−01−01" "2020−01−02" "2020−01−03" "2020−01−04" "2020−01−05" [6] "2020−01−06" "2020−01−07" "2020−01−08" "2020−01−09" "2020−01−10" [11] "2020−01−11" "2020−01−12" "2020−01−13" "2020−01−14" "2020−01−15" ...
Read MoreHow to concatenate two or more vectors in R?
The concatenation of vectors can be done by using combination function c. For example, if we have three vectors x, y, z then the concatenation of these vectors can be done as c(x,y,z). Also, we can concatenate different types of vectors at the same time using the same same function.Example1set.seed(999) x1
Read MoreWhat is the difference between creating a matrix by using matrix function or as.matrix function in R?
The difference between as.matrix and matrix function is that nrow argument or ncol argument are not helpful with as.matrix function but with matrix function we can use them. Therefore, we can actual define a matrix with matrix function but if we have a data frame or data table then it can be converted to matrix by using as.matrix function.Examples of creating matrix with as.matrix and matrix functionExample1M
Read MoreHow to calculate mahalanobis distance in R?
The Mahalanobis distance is the relative distance between two cases and the centroid, where centroid can be thought of as an overall mean for multivariate data. We can say that the centroid is the multivariate equivalent of mean. If the mahalanobis distance is zero that means both the cases are very same and positive value of mahalanobis distance represents that the distance between the two variables is large. In R, we can use mahalanobis function to find the malanobis distance.Example1y1
Read MoreMaximum Sum Increasing Subsequence using DP in C++ program
In this problem, we are given an array arr[] of size n. Our task is to create a program to find the maximum Sum Increasing Subsequence using DP in C++.Problem Description − To find the maximum sum increasing subsequence, we will be creating a subsequence in which the next element is greater than the current element.Let’s take an example to understand the problem, Inputarr[] = {4, 2, 3, 6, 5, 9}Output20ExplanationIncreasing subsequence with maximum sum: {2, 3, 6, 9} = 2 + 3 + 6 + 9 = 20Solution ApproachTo solve the problem using a dynamic Program Approach. We will ...
Read MoreHow to check if a matrix is invertible or not in R?
If the matrix is singular then it is not invertible and if it is non−singular then it is invertible. Therefore, we can check if a matrix is singular or not. We can use is.singular.matrix function of matrixcalc for this purpose. For example, if we have a matrix called M then to check whether it is invertible or not, we can use is.singular.matrix(M).Example1Loading matrixcalc package and creating a matrix −library(matrixcalc) M1
Read MoreHow to print a large number of values in R without index?
Whenever we print any vector then the left-hand side of the R window shows indexing, even if we have one value in the vector the index will be there. For example, if we print a vector that has value equal to 2 then the print output will be [1] 2, here [1] represents the index. If we want to print the vector without index then cat function can be used as shown in the below examples.Example1x1
Read MoreHow to change the repeated row names and column names to a sequence in a matrix in R?
To change the repeated row names and column names to a sequence, we first need to read those names in a vector then set them to row names and column names with make.unique function. For example, if a matrix has row names defined as A, B, A, B, A then it can be converted into A, B, A.1, B.1, A.2.Example1M1
Read More