std::gslice

 

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Genéricos operaciones numéricas Original: Generic numeric operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

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std::valarray

Las funciones miembro Original: Member functions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
valarray::valarray valarray::~valarray valarray::operator= valarray::operator[] valarray::swap valarray::size valarray::resize valarray::sum valarray::min valarray::max valarray::shift valarray::cshift valarray::apply	valarray::operator+ valarray::operator- valarray::operator~ valarray::operator! valarray::operator+= valarray::operator-= valarray::operator*= valarray::operator/= valarray::operator%= valarray::operator&= valarray::operator|= valarray::operator^= valarray::operator<<= valarray::operator>>=
Terceros funciones Original: Non-member functions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
swap (C++11) begin (C++11) end (C++11) abs exp log log10 pow sqrt sin cos tan asin acos atan atan2 sinh cosh tanh	operator* operator/ operator% operator+ operator- operator^ None operator& operator| operator<< operator>> operator&& operator None operator== operator!= operator< operator> operator<= operator>=
Clases de ayuda Original: Helper classes The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
slice_array gslice_array indirect_array	slice gslice mask_array

 

Defined in header <valarray>
class gslice;

std::gslice es el selector de clase que identifica un subconjunto de los índices de std::valarray definidas por un conjunto de múltiples niveles de avances y tamaños. Objetos de std::gslice tipo se puede utilizar como índices con operator[] valarray para seleccionar, por ejemplo, las columnas de una matriz multidimensional representado como un valarray .

Original:

std::gslice is the selector class that identifies a subset of std::valarray indices defined by a multi-level set of strides and sizes. Objects of type std::gslice can be used as indices with valarray's operator[] to select, for example, columns of a multidimensional array represented as a valarray.

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Dada la s valor inicial, una lista de los pasos i
j y una lista de tamaños d
j, un std::gslice construido a partir de estos valores se selecciona el conjunto de índices k
j=s+Σ
j(i
jd
j) .

Original:

Given the starting value s, a list of strides i
j and a list of sizes d
j, a std::gslice constructed from these values selects the set of indices k
j=s+Σ
j(i
jd
j).

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Por ejemplo, un GSlice con 3 índice de inicio, pasos {19,4,1} y longitudes {2,4,3} genera el siguiente conjunto de índices:

Original:

For example, a gslice with starting index 3, strides {19,4,1} and lengths {2,4,3} generates the following set of indices:

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3 + 0*19 + 0*4 + 0*1 = 3,
3 + 0*19 + 0*4 + 1*1 = 4,
3 + 0*19 + 0*4 + 2*1 = 5,
3 + 0*19 + 1*4 + 0*1 = 7,
3 + 0*19 + 1*4 + 1*1 = 8,
...
3 + 1*19 + 3*4 + 2*1 = 36

Es posible construir objetos std::gslice que seleccionan algunos de los índices más de una vez: si el ejemplo anterior utiliza el {1,1,1} pasos, los índices habría sido {3, 4, 5, 4, 5, 6, ...} . Gslices Solamente pueden utilizarse como argumentos a la versión const std::valarray::operator[] de lo contrario, el comportamiento no está definido .

Original:

It is possible to construct std::gslice objects that select some indices more than once: if the above example used the strides {1,1,1} , the indices would have been {3, 4, 5, 4, 5, 6, ...} . Such gslices may only be used as arguments to the const version of std::valarray::operator[], otherwise the behavior is undefined.

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Las funciones miembro

(constructor)	construye una GSlice Original: constructs a gslice The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (miembro público función)
start	accede al inicio de la GSlice Original: accesses the start of the gslice The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (miembro público función)
stride	accede a la gran variedad de pasos de la GSlice Original: accesses the array of strides of the gslice The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (miembro público función)
size	accede a la matriz de sizees de la GSlice Original: accesses the array of sizees of the gslice The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (miembro público función)

Ejemplo

muestra el uso de gslices para hacer frente a las columnas de una matriz 3D

Original:

demonstrates the use of gslices to address columns of a 3D array

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#include <iostream>
#include <valarray>
void test_print(std::valarray<int>& v, int rows, int cols, int planes)
{
    for(int r=0; r<rows; ++r) {
        for(int c=0; c<cols; ++c) {
            for(int z=0; z<planes; ++z)
                std::cout << v[r*cols*planes + c*planes + z] << ' ';
            std::cout << '\n';
        }
        std::cout << '\n';
    }
}
int main()
{
    std::valarray<int> v = // 3d array: 2 x 4 x 3 elements
    { 111,112,113 , 121,122,123 , 131,132,133 , 141,142,143,
      211,212,213 , 221,222,223 , 231,232,233 , 241,242,243};
    // int ar3d[2][4][3]
    std::cout << "Initial 2x4x3 array:\n";
    test_print(v, 2, 4, 3);
 
    // update every value in the first columns of both planes
    v[std::gslice(0, {2, 4}, {4*3, 3})] = 1; // two level one strides of 12 elements
                                             // then four level two strides of 3 elements
 
    // subtract the third column from the second column in the 1st plane
    v[std::gslice(1, {1, 4}, {4*3, 3})] -= v[std::gslice(2, {1, 4}, {4*3, 3})];
 
    std::cout << "After column operations: \n";
    test_print(v, 2, 4, 3);
}

Output:

Initial 2x4x3 array:
111 112 113
121 122 123
131 132 133
141 142 143
 
211 212 213
221 222 223
231 232 233
241 242 243
 
After column operations:
1 -1 113
1 -1 123
1 -1 133
1 -1 143
 
1 212 213
1 222 223
1 232 233
1 242 243

Ver también

operator[]	obtener / establecer elemento valarray, sector u máscara Original: get/set valarray element, slice, or mask The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (miembro público función)
slice	BLAS-como una rebanada de valarray: índice de inicio, duración, ritmo Original: BLAS-like slice of a valarray: starting index, length, stride The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (clase)
gslice_array	proxy para un subconjunto de un valarray después de aplicar un GSlice Original: proxy to a subset of a valarray after applying a gslice The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (clase de plantilla)