points = [(1,1),(5,3)] p1 = points[0] p1[0] = p1[0] * 60 print(p1[0]) 要如何修改
时间: 2023-11-01 21:06:40 浏览: 21
这段代码有误,因为元组是不可变的,所以不能修改元组中的元素。如果想要修改元组中的元素,需要重新创建一个新的元组来替换原来的元组。可以按照以下方式修改代码:
```python
points = [(1,1),(5,3)]
p1 = list(points[0]) # 将元组转换为列表
p1[0] = p1[0] * 60
points[0] = tuple(p1) # 将修改后的列表转换为元组并替换原来的元组
print(points[0][0])
```
输出结果为 60。
相关问题
qt多变// 判断一个顶点是否为耳朵 bool isEar(QPointF p0, QPointF p1, QPointF p2, QVector<QPointF> points)
判断一个顶点是否为耳朵需要判断以下三个条件:
1. 该顶点所对应的角度是否为凸角;
2. 该顶点是否在多边形内部;
3. 该顶点是否被多边形中的其他顶点所包含。
以下是判断一个顶点是否为耳朵的实现代码:
```cpp
bool isEar(QPointF p0, QPointF p1, QPointF p2, QVector<QPointF> points)
{
// 判断顶点所对应的角度是否为凸角
QLineF line1(p0, p1);
QLineF line2(p1, p2);
qreal angle = line1.angleTo(line2);
if (angle > 180) {
angle = 360 - angle;
}
if (angle >= 180) {
return false;
}
// 判断顶点是否在多边形内部
QPolygonF polygon(points);
if (!polygon.containsPoint(p0, Qt::OddEvenFill)) {
return false;
}
// 判断顶点是否被多边形中的其他顶点所包含
for (int i = 0; i < points.size(); i++) {
if (points[i] == p0 || points[i] == p1 || points[i] == p2) {
continue;
}
QLineF line(points[i], p0);
if (polygon.containsPoint(points[i], Qt::OddEvenFill) && line.intersect(line1, nullptr) == QLineF::NoIntersection && line.intersect(line2, nullptr) == QLineF::NoIntersection) {
return false;
}
}
return true;
}
```
其中,points 是多边形的顶点集合。函数返回值为 true 表示该顶点是一个耳朵。
x0 = str((p2[0] - p1[0]) / 2 + p1[0]) y0 = str((p2[1] - p1[1]) / 2 + p1[1])
As an AI language model, I am not sure what the context or purpose of this code is. However, based on my understanding of Python syntax, it seems like these two lines of code are calculating the midpoint between two given points (p1 and p2), and storing the x and y coordinates of the midpoint in variables x0 and y0 respectively.
The formula used to calculate the midpoint between two points is:
midpoint = ((x1 + x2) / 2, (y1 + y2) / 2)
So, the code you provided is using this formula to calculate the x-coordinate of the midpoint by subtracting the x-coordinate of p1 from the average of the x-coordinates of p1 and p2. Similarly, it is calculating the y-coordinate of the midpoint by subtracting the y-coordinate of p1 from the average of the y-coordinates of p1 and p2. The result is then converted to a string and stored in the variables x0 and y0.