blind_function.md

blind_function

Prototype

template<class Function>
auto blind_function(Function function, any_blind_raster raster);

Description

Apply a function on the raster wrapped by any_blind_raster.

Definition

<pronto/raster/blind_function.h> (open in Github)

Requirements on types

Function must be Callable with with any_raster<T> as the input argument, whereby T must be a supported type((bool, short, unsigned int, int, unsigned short, unsigned char, float, double). The return type of the Function Callable must be independent of T.

Preconditions

The input raster must be initialized, i.e. not be in the default-constructed state.

Complexity

The complexity is that of function(any_raster<T>)

Example of use

//example_blind_function.cpp

#include <pronto/raster/any_blind_raster.h>
#include <pronto/raster/blind_function.h>
#include <pronto/raster/io.h>
#include <pronto/raster/plot_raster.h>
#include <pronto/raster/transform_raster_view.h>

namespace pr = pronto::raster;

struct square
{
public:
  template<class T>
  pr::any_blind_raster operator()(const pr::any_raster<T>& raster) const
  {
    auto sq_fun = [](const T& v) {return v * v; };
    auto result_typed = pr::transform(sq_fun, raster);

    // wrapping as any_blind_raster because the return type must be 
    // independent of T.
    return pr::make_any_blind_raster(result_typed);
  }
};

int main()
{
  // prepare a raster in separate scope
  {
    auto raster = pr::create<int>("demo.tif", 3, 4, GDT_Byte);
    auto i = 0;
    for (auto&& v : raster) {
      i = (i + 3) % 7;
      v = i;
    }
  }

  // Open without specifying the type of the raster
  pr::any_blind_raster ras = pr::open_any("demo.tif");
  pr::any_blind_raster ras_sq = pr::blind_function(square{}, ras);
  plot_raster(ras);
  plot_raster(ras_sq);
  return 0;
}

Output:

Rows: 3, Cols: 4, Value type: unsigned char
3       6       2       5
1       4       0       3
6       2       5       1

Rows: 3, Cols: 4, Value type: int
9       36      4       25
1       16      0       9
36      4       25      1

Notes

See also

any_blind_raster,make_any_blind_raster, open_any, blind_function