knapply

library(shiny)

server <- function(input, output) {
  output$input_value <- renderPrint({
    cat(input$slide)                # cat() is an alternative to print(), see: ?cat()
  })                                ## I'm only using it here to hide the index that
                                    ## would be otherwise outputted. For example:
                                    ## > print(2)
                                    ## [1] 2
                                    ## > cat(2)

knapply

r_length <- function(x) {
  out <- 0L
  for (i in x) {
    out <- out + 1L
  }
  out
}

r_vector <- 1:20
r_length(r_vector) 

knapply

def py_length(x):
  out = 0  
  for i in x:
    out += 1
  return out

py_generator = range(1, 21)
result = py_length(py_generator)
print(result)
#> 20

knapply

#include <Rcpp.h>
using namespace Rcpp;

// [[Rcpp::export]]
int cpp_length(NumericVector x) {
  int out = 0;
  for (NumericVector::iterator iter = x.begin(); iter != x.end(); iter++) {
    out++;
  }
  return out;

knapply

r_vector <- 1:20
length(r_vector)
#> [1] 20

knapply

py_generator = range(1, 21)

result = len(py_generator)

print(result)
#> 20

knapply

#include <Rcpp.h>
using namespace Rcpp;

// [[Rcpp::export]]
int cpp_size(NumericVector x) {
  return x.size();
}

/*** R
cpp_size(1:20)

knapply

#include <iostream>  // std::cout, std::endl
#include <vector>    // std::vector

using std::cout;
using std::endl;
using std::vector;

int length(vector<double> &x) {
	int out = 0;

knapply

import numpy as np

numpy_array = np.array(range(1, 21))

result = np.size(numpy_array)

print(result)
#> 20

knapply

#include <iostream>  // std::cout, std::endl
#include <vector>    // std::vector

using std::cout;
using std::endl;
using std::vector;

int main() {
    vector<double> v{ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 };