5000x2x200 doubl
时间: 2024-08-28 16:03:15 浏览: 22
要计算5000乘以2再乘以200的double类型结果,我们不需要直接编写Python代码来完成这个简单算术操作,因为Python的`*`运算符会自动处理数值类型的转换。但如果你需要演示双精度浮点数(double)的乘法过程,我们可以使用numpy库,因为它提供了高效的多维数组操作。
```python
import numpy as np
# 创建一个double类型的2D数组
array_2d = np.zeros((2, 200), dtype=np.float64)
# 通过numpy计算并赋值
result = 5000 * 2 * array_2d
```
这里,`np.zeros((2, 200), dtype=np.float64)`创建了一个2行200列全零的double类型二维数组。然后,我们将5000乘以2的结果分配给整个数组,这样每个元素都会得到相应的乘积。
请注意,`dtype=np.float64`用于指定double类型,如果不需要这个类型转换,可以直接省略。
相关问题
有一个区域,区域中有很多矩形,矩形左上角和右下角的坐标分别是(x1,y1),(x2,y2),矩形类为class QRect { public: DTYPE_FEATURE_ID id = 0; double x1; double y1; double x2; double y2; QRect(DTYPE_FEATURE_ID id, double x1, double y1, double x2, double y2) : id(id), x1(x1), y1(y1), x2(x2), y2(y2) {} QRect(double x1, double y1, double x2, double y2) : x1(x1), y1(y1), x2(x2), y2(y2) {} bool Contains(double x, double y) { return x1 <= x && x<= x2 && y <= y1 && y2 <= y; } };每个矩形有自己的id,如何通过四叉树的方式用c++实现快速判断,任意一个点的坐标(x,y)在区域中的那个矩形中,返回矩形的id
可以通过四叉树来实现快速判断一个点落在哪个矩形中。
首先,定义四叉树的节点类型,包含矩形信息及四个子节点指针:
```c++
struct QuadTreeNode {
QRect rect; // 矩形信息
QuadTreeNode* children[4]; // 四个子节点指针
QuadTreeNode(const QRect& rect) : rect(rect) {
memset(children, 0, sizeof(children));
}
};
```
接着,定义四叉树的构建函数,这里采用递归方式实现。如果当前节点所代表的矩形不包含目标点,则返回空指针,否则检查子节点中是否有包含目标点的矩形,如果有则递归进入该子节点,否则返回当前节点。
```c++
QuadTreeNode* buildQuadTree(const std::vector<QRect>& rects, const QRect& boundary) {
QuadTreeNode* node = new QuadTreeNode(boundary);
if (rects.empty()) return node;
if (rects.size() == 1) {
node->rect = rects[0];
return node;
}
// 将 boundary 分成四个子区域
double xmid = (boundary.x1 + boundary.x2) / 2.0;
double ymid = (boundary.y1 + boundary.y2) / 2.0;
QRect nw(boundary.x1, ymid, xmid, boundary.y2);
QRect ne(xmid, ymid, boundary.x2, boundary.y2);
QRect sw(boundary.x1, boundary.y1, xmid, ymid);
QRect se(xmid, boundary.y1, boundary.x2, ymid);
std::vector<QRect> nwRects, neRects, swRects, seRects;
for (const QRect& r : rects) {
if (nw.Contains(r.x1, r.y2) || nw.Contains(r.x2, r.y1) || nw.Contains(r.x2, r.y2)) {
nwRects.push_back(r);
} else if (ne.Contains(r.x1, r.y2) || ne.Contains(r.x2, r.y1) || ne.Contains(r.x1, r.y1)) {
neRects.push_back(r);
} else if (sw.Contains(r.x1, r.y2) || sw.Contains(r.x2, r.y1) || sw.Contains(r.x2, r.y2)) {
swRects.push_back(r);
} else if (se.Contains(r.x1, r.y2) || se.Contains(r.x2, r.y1) || se.Contains(r.x1, r.y1)) {
seRects.push_back(r);
}
}
if (!nwRects.empty()) node->children[0] = buildQuadTree(nwRects, nw);
if (!neRects.empty()) node->children[1] = buildQuadTree(neRects, ne);
if (!swRects.empty()) node->children[2] = buildQuadTree(swRects, sw);
if (!seRects.empty()) node->children[3] = buildQuadTree(seRects, se);
return node;
}
```
最后,定义一个函数用来查询目标点所在的矩形的id,也是采用递归方式实现。如果当前节点为叶子节点,则返回该节点代表的矩形的id;否则检查子节点中是否有包含目标点的矩形,如果有则递归进入该子节点,否则返回当前节点代表的矩形的id。
```c++
DTYPE_FEATURE_ID queryQuadTree(QuadTreeNode* node, double x, double y) {
if (!node || !node->rect.Contains(x, y)) return 0;
if (!node->children[0] && !node->children[1] && !node->children[2] && !node->children[3]) {
return node->rect.id;
}
for (int i = 0; i < 4; ++i) {
DTYPE_FEATURE_ID id = queryQuadTree(node->children[i], x, y);
if (id) return id;
}
return node->rect.id;
}
```
完整代码如下:
```c++
#include <cstring>
#include <vector>
typedef int DTYPE_FEATURE_ID;
struct QRect {
DTYPE_FEATURE_ID id = 0;
double x1;
double y1;
double x2;
double y2;
QRect(DTYPE_FEATURE_ID id, double x1, double y1, double x2, double y2)
: id(id), x1(x1), y1(y1), x2(x2), y2(y2) {}
QRect(double x1, double y1, double x2, double y2) : x1(x1), y1(y1), x2(x2), y2(y2) {}
bool Contains(double x, double y) {
return x1 <= x && x <= x2 && y <= y1 && y2 <= y;
}
};
struct QuadTreeNode {
QRect rect;
QuadTreeNode* children[4];
QuadTreeNode(const QRect& rect) : rect(rect) {
memset(children, 0, sizeof(children));
}
};
QuadTreeNode* buildQuadTree(const std::vector<QRect>& rects, const QRect& boundary) {
QuadTreeNode* node = new QuadTreeNode(boundary);
if (rects.empty()) return node;
if (rects.size() == 1) {
node->rect = rects[0];
return node;
}
double xmid = (boundary.x1 + boundary.x2) / 2.0;
double ymid = (boundary.y1 + boundary.y2) / 2.0;
QRect nw(boundary.x1, ymid, xmid, boundary.y2);
QRect ne(xmid, ymid, boundary.x2, boundary.y2);
QRect sw(boundary.x1, boundary.y1, xmid, ymid);
QRect se(xmid, boundary.y1, boundary.x2, ymid);
std::vector<QRect> nwRects, neRects, swRects, seRects;
for (const QRect& r : rects) {
if (nw.Contains(r.x1, r.y2) || nw.Contains(r.x2, r.y1) || nw.Contains(r.x2, r.y2)) {
nwRects.push_back(r);
} else if (ne.Contains(r.x1, r.y2) || ne.Contains(r.x2, r.y1) || ne.Contains(r.x1, r.y1)) {
neRects.push_back(r);
} else if (sw.Contains(r.x1, r.y2) || sw.Contains(r.x2, r.y1) || sw.Contains(r.x2, r.y2)) {
swRects.push_back(r);
} else if (se.Contains(r.x1, r.y2) || se.Contains(r.x2, r.y1) || se.Contains(r.x1, r.y1)) {
seRects.push_back(r);
}
}
if (!nwRects.empty()) node->children[0] = buildQuadTree(nwRects, nw);
if (!neRects.empty()) node->children[1] = buildQuadTree(neRects, ne);
if (!swRects.empty()) node->children[2] = buildQuadTree(swRects, sw);
if (!seRects.empty()) node->children[3] = buildQuadTree(seRects, se);
return node;
}
DTYPE_FEATURE_ID queryQuadTree(QuadTreeNode* node, double x, double y) {
if (!node || !node->rect.Contains(x, y)) return 0;
if (!node->children[0] && !node->children[1] && !node->children[2] && !node->children[3]) {
return node->rect.id;
}
for (int i = 0; i < 4; ++i) {
DTYPE_FEATURE_ID id = queryQuadTree(node->children[i], x, y);
if (id) return id;
}
return node->rect.id;
}
int main() {
std::vector<QRect> rects = {
QRect(1, 0, 0, 1, 1),
QRect(2, 1, 1, 2, 2),
QRect(3, 2, 2, 3, 3),
QRect(4, 3, 3, 4, 4),
};
QuadTreeNode* root = buildQuadTree(rects, QRect(0, 0, 4, 4));
double x = 2.5, y = 3.5;
DTYPE_FEATURE_ID id = queryQuadTree(root, x, y);
printf("Point (%g, %g) is in rect #%d\n", x, y, id);
return 0;
}
```
本题要求实现一个函数,对给定平面任意两点坐标(x 1 ,y 1 )和(x 2 ,y 2 ),求这两点之间的距离。 函数接口定义: double dist( double x1, double y1, double x2, double y2 ); 其中用户传入的参数为平面上两个点的坐标(x1, y1)和(x2, y2),函数dist应返回两点间的距离。 裁判测试程序样例: #include <stdio.h> #include <math.h> double dist( double x1, double y1, double x2, double y2 ); int main() { double x1, y1, x2, y2; scanf("%lf %lf %lf %lf", &x1, &y1, &x2, &y2); printf("dist = %.2f\n", dist(x1, y1, x2, y2)); return 0; } /* 你的代码将被嵌在这里 */ 输入样例: 10 10 200 100
实现代码如下:
```
#include <stdio.h>
#include <math.h>
double dist(double x1, double y1, double x2, double y2) {
double dx = x2 - x1;
double dy = y2 - y1;
double distance = sqrt(dx * dx + dy * dy);
return distance;
}
int main() {
double x1, y1, x2, y2;
scanf("%lf %lf %lf %lf", &x1, &y1, &x2, &y2);
printf("dist = %.2f\n", dist(x1, y1, x2, y2));
return 0;
}
```
在函数dist中,先计算出两点在x轴和y轴上的距离,然后根据勾股定理计算出两点之间的距离,最后返回距离值。在main函数中,读入四个double类型的变量,将它们作为参数传递给dist函数,并输出dist函数的返回值。