std::gslice

 

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std::valarray

Member-Funktionen 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>>=
Non-Member-Funktionen 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>=
Helper-Klassen 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

 

definiert in Header <valarray>
class gslice;

std::gslice ist der Selektor Klasse, die eine Teilmenge von std::valarray Indizes nach einer mehrstufigen Satz von Schritten und Größen definiert identifiziert. Objekte des Typs std::gslice als Indizes mit den valarray operator[] kann verwendet werden, um auszuwählen, beispielsweise Spalten einer multidimensionalen Array als valarray dargestellt .

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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Angesichts der Startwert s, eine Liste von Schritten i
j und eine Liste von Größen d
j wählt ein std::gslice aus diesen Werten aufgebaut des Satzes von Indizes 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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Zum Beispiel erzeugt ein GSlice mit Startindex 3 schreitet {19,4,1} und Längen {2,4,3} den folgenden Satz von Indizes:

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 ist möglich, Objekte, die einige std::gslice Indizes auszuwählen mehr als einmal zu konstruieren: wenn das obige Beispiel verwendet den Schritten {1,1,1} die Indizes würde {3, 4, 5, 4, 5, 6, ...} gewesen. Solche gslices darf nur als Argumente für die const-Version von std::valarray::operator[] verwendet werden, da sonst das Verhalten undefiniert ist .

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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Member-Funktionen

(constructor)	konstruiert eine 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. (öffentliche Elementfunktion)
start	greift auf den Beginn des 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. (öffentliche Elementfunktion)
stride	greift auf die Reihe von Schritten der 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. (öffentliche Elementfunktion)
size	greift das Array von sizees der 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. (öffentliche Elementfunktion)

Beispiel

zeigt die Verwendung von gslices zum Spalten eines 3D-Feld anzusprechen

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

Siehe auch

operator[]	get / set valarray Element, Scheibe, oder Maske 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. (öffentliche Elementfunktion)
slice	BLAS-ähnliche Scheibe eines valarray: Startindex, Länge, Schritt 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. (Klasse)
gslice_array	Proxy auf eine Teilmenge eines valarray nach Anwendung eines 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. (Klassen-Template)