Assign a std::vector to a std::valarray

Question

I have a `vector`, so a table (matrix) of values. Columns contains position and velocity of a planet, so rows stores data of the same planet. I want to transform a row in a `valarray` because I need math operations. Then I want to store the valarrays (the planets) in a vector. I tried like this: ``` vector> corps_tmp=configFile.get_corps(); // The function returns a vector> valarray corpX; for (int i(0); i < corps_tmp.size(); i++) { corpX = corps_tmp[i]; // I want to save the first row of the vector> on the valarray corps.push_back(corpX); // I want to ''add'' the valarray to a vector. corpX = 0; } ``` This code doesn't works and I obtain an error around the assignment of a vector to a valarray (apparently not permitted). Is there any way to achieve in a simple way what I tried to do?

Accepted Answer

To create a valarray from a vector:

```
std::valarray<double> corpX(corps_tmp[i].data(), corps_tmp[i].size());
```

To write the data back into a vector:

```
corps_tmp[i].assign(std::begin(corpX), std::end(corpX));
```

Assign a std::vector to a std::valarray

Solution

Problem