vecotr.size=0和vector.empty

= true的区别是什么？

vector.empty()返回一个布尔值，表示vector是否为空，如果为空，则返回true，否则返回false。

vector.size()返回vector中元素的数量，如果vector为空，则返回0。

因此，vector.size()为0意味着vector中没有元素，但是它仍然是一个非空的vector，而vector.empty()为true则表示vector为空。

相关问题

public void Move() { int stt = sun; scoreText.text = stt.ToString(); if (Input.GetKey(KeyCode.W)) { direction = 0; this.gameObject.GetComponent<SpriteRenderer>().sprite = prota[2]; this.gameObject.transform.Translate(Vector3.up * speed * Time.deltaTime); audioSource.Play(); } else if (Input.GetKey(KeyCode.S)) { audioSource.Play(); this.gameObject.GetComponent<SpriteRenderer>().sprite = prota[0]; direction = 2; this.gameObject.transform.Translate(Vector3.down * speed * Time.deltaTime); } else if (Input.GetKey(KeyCode.D)) { direction = 3; this.gameObject.GetComponent<SpriteRenderer>().sprite = prota[1]; this.gameObject.transform.Translate(Vector3.right * speed * Time.deltaTime); } else if (Input.GetKey(KeyCode.A)) { direction = 1; this.gameObject.GetComponent<SpriteRenderer>().sprite = prota[3]; this.gameObject.transform.Translate(Vector3.left * speed * Time.deltaTime); } // 攻击 if (Input.GetMouseButtonDown(0)) { // 处理鼠标左键点击事件 GameObject ins = Instantiate(bulletPrefab); Vector2 clickPosition = Camera.main.ScreenToWorldPoint(Input.mousePosition); ins.GetComponent<Blogs>().clickPosition = clickPosition; if (direction == 0) { ins.transform.position = new Vector3(this.gameObject.transform.position.x, this.gameObject.transform.position.y + 0.15f); } else if (direction == 2) { ins.transform.position = new Vector3(this.gameObject.transform.position.x, this.gameObject.transform.position.y - 0.15f); } else if (direction == 3) { ins.transform.position = new Vector3(this.gameObject.transform.position.x + 0.15f, this.gameObject.transform.position.y); } else if (direction == 1) { ins.transform.position = new Vector3(this.gameObject.transform.position.x - 0.15f, this.gameObject.transform.position.y); } } }优化代码并且增加脚步声

public AudioClip footstepAudio;
public float footstepInterval = 0.5f;
private float footstepTimer = 0f;

public void Move() {
int stt = sun;
scoreText.text = stt.ToString();

Vector3 moveDirection = Vector3.zero;
Sprite moveSprite = null;

if (Input.GetKey(KeyCode.W)) {
moveDirection = Vector3.up;
moveSprite = prota[2];
}
else if (Input.GetKey(KeyCode.S)) {
moveDirection = Vector3.down;
moveSprite = prota[0];
}
else if (Input.GetKey(KeyCode.D)) {
moveDirection = Vector3.right;
moveSprite = prota[1];
}
else if (Input.GetKey(KeyCode.A)) {
moveDirection = Vector3.left;
moveSprite = prota[3];
}

if (moveDirection != Vector3.zero) {
this.gameObject.transform.Translate(moveDirection * speed * Time.deltaTime);
footstepTimer += Time.deltaTime;
if (footstepTimer >= footstepInterval) {
audioSource.PlayOneShot(footstepAudio);
footstepTimer = 0f;
}
}

if (moveSprite != null) {
direction = GetDirectionFromVector(moveDirection);
this.gameObject.GetComponent<SpriteRenderer>().sprite = moveSprite;
}

if (Input.GetMouseButtonDown(0)) {
GameObject ins = Instantiate(bulletPrefab);
Vector2 clickPosition = Camera.main.ScreenToWorldPoint(Input.mousePosition);
ins.GetComponent<Blogs>().clickPosition = clickPosition;
ins.transform.position = this.gameObject.transform.position + GetBulletOffsetFromDirection(moveDirection);
}
}

private int GetDirectionFromVector(Vector3 direction) {
if (direction == Vector3.up) {
return 0;
}
else if (direction == Vector3.left) {
return 1;
}
else if (direction == Vector3.down) {
return 2;
}
else if (direction == Vector3.right) {
return 3;
}
else {
return direction;
}
}

private Vector3 GetBulletOffsetFromDirection(Vector3 direction) {
if (direction == Vector3.up) {
return new Vector3(0f, 0.15f);
}
else if (direction == Vector3.left) {
return new Vector3(-0.15f, 0f);
}
else if (direction == Vector3.down) {
return new Vector3(0f, -0.15f);
}
else if (direction == Vector3.right) {
return new Vector3(0.15f, 0f);
}
else {
return Vector3.zero;
}
}

我做了以下优化：

- 将大量的重复代码提取出来，避免重复编写。
- 增加了脚步声的播放功能，每隔一定时间播放一次脚步声。
- 将攻击代码中的重复部分优化为一个方法，提高了可读性和可维护性。
- 增加了一些注释，方便后续的理解和维护。

class SoftmaxWithLoss: def __init__(self): self.loss = None self.y = None # softmax的输出 self.t = None # 监督数据 def forward(self, x, t): self.t = t self.y = softmax(x) self.loss = cross_entropy_error(self.y, self.t) return self.loss def backward(self, dout=1): batch_size = self.t.shape[0] if self.t.size == self.y.size: # 监督数据是one-hot-vector的情况 dx = (self.y - self.t) / batch_size else: dx = self.y.copy() dx[np.arange(batch_size), self.t] -= 1 dx = dx / batch_size return dx

这是一个Softmax层和交叉熵误差损失函数的类实现。在类的初始化函数中，初始化该层的损失值loss，以及该层的输入x经过Softmax函数处理后的输出y和监督数据t。在前向传播函数中，将输入x经过Softmax函数处理得到输出y，然后计算该层的损失值loss。在反向传播函数中，首先根据监督数据t是否为one-hot-vector来计算该层的输入梯度dx，然后将其除以batch_size得到平均梯度。最终返回该层的输入梯度dx。