In Rcpp, you can erase zeros from a vector element using C++ code within an Rcpp function. Here's how you can achieve this:
```cpp
#include <Rcpp.h>
using namespace Rcpp;
// Function to erase zeros from a vector element
NumericVector eraseZeros(NumericVector x) {
NumericVector result;
for (int i = 0; i < x.size(); i++) {
if (x[i] != 0) {
result.push_back(x[i]);
}
}
return result;
}
// [[Rcpp::export]]
NumericVector eraseZerosInRcpp(NumericVector x) {
return eraseZeros(x);
}
/*** R
# Example usage
x <- c(1, 0, 2, 0, 3, 0, 4)
result <- eraseZerosInRcpp(x)
cat("Original vector: ", x, "\n")
cat("Vector with zeros erased: ", result, "\n")
*/
```
In this code:
1. We define a function `eraseZeros` that takes a `NumericVector` as input and creates a new `NumericVector` called `result`.
2. We iterate through each element of the input vector `x`. If the element is not equal to zero, we append it to the `result` vector.
3. Finally, we return the `result` vector containing the non-zero elements.
The `eraseZerosInRcpp` function is marked with `[[Rcpp::export]]`, which makes it accessible from R.
In the R code section, we provide an example usage of the `eraseZerosInRcpp` function.
Here's how you can use the function in R:
```R
x <- c(1, 0, 2, 0, 3, 0, 4)
result <- eraseZerosInRcpp(x)
cat("Original vector: ", x, "\n")
cat("Vector with zeros erased: ", result, "\n")
```
This will remove the zeros from the input vector and print both the original vector and the vector with zeros erased.