It is fairly easy to incorporate C++ code into R programs using the Rcpp package. Definitely worth the effort to learn how to do this.
On Sun, Dec 15, 2019 at 5:48 AM Boris Steipe <boris.ste...@utoronto.ca> wrote: > > See this thread why that's a bad idea ... > https://stackoverflow.com/questions/26080716/merge-sort-in-r > > ... and use the code given there, or give us some context why a literal > translation would be important to you. > > Cheers, > Boris > > > > > > On 2019-12-15, at 05:37, Александр Дубровский <dubrovvssk...@gmail.com> > > wrote: > > > > /* Iterative C program for merge sort */ > > #include<stdlib.h> > > #include<stdio.h> > > > > /* Function to merge the two haves arr[l..m] and arr[m+1..r] of array arr[] > > */ > > void merge(int arr[], int l, int m, int r); > > > > // Utility function to find minimum of two integers > > int min(int x, int y) { return (x<y)? x :y; } > > > > > > /* Iterative mergesort function to sort arr[0...n-1] */ > > void mergeSort(int arr[], int n) > > { > > int curr_size; // For current size of subarrays to be merged > > // curr_size varies from 1 to n/2 > > int left_start; // For picking starting index of left subarray > > // to be merged > > > > // Merge subarrays in bottom up manner. First merge subarrays of > > // size 1 to create sorted subarrays of size 2, then merge subarrays > > // of size 2 to create sorted subarrays of size 4, and so on. > > for (curr_size=1; curr_size<=n-1; curr_size = 2*curr_size) > > { > > // Pick starting point of different subarrays of current size > > for (left_start=0; left_start<n-1; left_start += 2*curr_size) > > { > > // Find ending point of left subarray. mid+1 is starting > > // point of right > > int mid = min(left_start + curr_size - 1, n-1); > > > > int right_end = min(left_start + 2*curr_size - 1, n-1); > > > > // Merge Subarrays arr[left_start...mid] & > > arr[mid+1...right_end] > > merge(arr, left_start, mid, right_end); > > } > > } > > } > > > > /* Function to merge the two haves arr[l..m] and arr[m+1..r] of array arr[] > > */ > > void merge(int arr[], int l, int m, int r) > > { > > int i, j, k; > > int n1 = m - l + 1; > > int n2 = r - m; > > > > /* create temp arrays */ > > int L[n1], R[n2]; > > > > /* Copy data to temp arrays L[] and R[] */ > > for (i = 0; i < n1; i++) > > L[i] = arr[l + i]; > > for (j = 0; j < n2; j++) > > R[j] = arr[m + 1+ j]; > > > > /* Merge the temp arrays back into arr[l..r]*/ > > i = 0; > > j = 0; > > k = l; > > while (i < n1 && j < n2) > > { > > if (L[i] <= R[j]) > > { > > arr[k] = L[i]; > > i++; > > } > > else > > { > > arr[k] = R[j]; > > j++; > > } > > k++; > > } > > > > /* Copy the remaining elements of L[], if there are any */ > > while (i < n1) > > { > > arr[k] = L[i]; > > i++; > > k++; > > } > > > > /* Copy the remaining elements of R[], if there are any */ > > while (j < n2) > > { > > arr[k] = R[j]; > > j++; > > k++; > > } > > } > > > > /* Function to print an array */ > > void printArray(int A[], int size) > > { > > int i; > > for (i=0; i < size; i++) > > printf("%d ", A[i]); > > printf("\n"); > > } > > > > /* Driver program to test above functions */ > > int main() > > { > > int arr[] = {12, 11, 13, 5, 6, 7}; > > int n = sizeof(arr)/sizeof(arr[0]); > > > > printf("Given array is \n"); > > printArray(arr, n); > > > > mergeSort(arr, n); > > > > printf("\nSorted array is \n"); > > printArray(arr, n); > > return 0; > > } > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > > and provide commented, minimal, self-contained, reproducible code. > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
