lmda 8 集合比较
时间: 2024-01-11 13:18:45 浏览: 24
Lambda 表达式是一种匿名函数,它可以作为参数传递给方法或存储在变量中。在 Java 8 中,Lambda 表达式被引入以简化代码和提高可读性。Lambda 表达式可以用于集合比较,例如对集合进行排序、筛选和映射等操作。
下面是一个使用 Lambda 表达式对集合进行排序的示例:
```java
List<String> names = Arrays.asList("Alice", "Bob", "Charlie", "David");
Collections.sort(names, (a, b) -> a.compareTo(b));
```
这个示例中,我们使用 `Collections.sort` 方法对 `names` 集合进行排序。第二个参数是一个 Lambda 表达式,它定义了一个比较器,用于比较两个字符串的大小关系。
Lambda 表达式的语法如下:
```
(parameters) -> expression
```
或者
```
(parameters) -> { statements; }
```
其中,`parameters` 是参数列表,可以为空或包含一个或多个参数;`expression` 是单个表达式,用于计算 Lambda 表达式的返回值;`statements` 是一组语句,用于计算 Lambda 表达式的返回值。
相关问题
fetch("https://can.ctrip.com/api/product/hotelfilter", { "headers": { "accept": "application/json, text/javascript, */*; q=0.01", "accept-language": "zh-CN,zh;q=0.9", "authorization": "eyJhbGciOiJIUzUxMiJ9.eyJzdWIiOiI3MDQxMiIsInVzZXJuYW1lIjoiWFJUWDA5MjUiLCJ1dWlkIjoiTG9naW5jMTQ4M2NiNy1lMDA0LTQyMWMtYWM2MS04YjVmOGYyYjZiYTciLCJyb2xlTmFtZXMiOlsiUk9MRV9BRE1JTiJdLCJleHAiOjE2NzQwMzU4MDZ9.4uxlgs29BIVP-KKlyHtOkTV-9Dv7muB65MCnA4nstPaVRwqHhT3Imw-8b8eHUdKZhY-l1Z7OHxsw2jAS2NWShQ", "content-type": "application/json", "sec-ch-ua": "\"Not?A_Brand\";v=\"8\", \"Chromium\";v=\"108\", \"Google Chrome\";v=\"108\"", "sec-ch-ua-mobile": "?0", "sec-ch-ua-platform": "\"Windows\"", "sec-fetch-dest": "empty", "sec-fetch-mode": "cors", "sec-fetch-site": "same-origin", "syslng": "zhCN", "x-requested-with": "XMLHttpRequest" }, "referrer": "https://can.ctrip.com/index", "referrerPolicy": "strict-origin-when-cross-origin", "body": "{\"cityid\":\"2\",\"countryid\":\"1\",\"currency\":\"CNY\"}", "method": "POST", "mode": "cors", "credentials": "include" }); 转成 python 代码
import requests
url = "https://can.ctrip.com/api/product/hotelfilter"
headers = {
"accept": "application/json, text/javascript, */*; q=0.01",
"accept-language": "zh-CN,zh;q=0.9",
"authorization": "eyJhbGciOiJIUzUxMiJ9.eyJzdWIiOiI3MDQxMiIsInVzZXJuYW1lIjoiWFJUWDA5MjUiLCJ1dWlkIjoiTG9naW5jMTQ4M2NiNy1lMDA0LTQyMWMtYWM2MS04YjVmOGYyYjZiYTciLCJyb2xlTmFtZXMiOlsiUk9MRV9BRE1JTiJdLCJleHAiOjE2NzQwMzU4MDZ9.4uxlgs29BIVP-KKlyHtOkTV-9Dv7muB65MCnA4nstPaVRwqHhT3Imw-8b8eHUdKZhY-l1Z7OHxsw2jAS2NWShQ",
"content-type": "application/json",
"sec-ch-ua": "\"Not?A_Brand\";v=\"8\", \"Chromium\";v=\"108\", \"Google Chrome\";v=\"108\"",
"sec-ch-ua-mobile": "?0",
"sec-ch-ua-platform": "\"Windows\"",
"sec-fetch-dest": "empty",
"sec-fetch-mode": "cors",
"sec-fetch-site": "same-origin",
"syslng": "zhCN",
"x-requested-with": "XMLHttpRequest"
}
data = {"cityid":"2","countryid":"1","currency":"CNY"}
response = requests.post(url, headers=headers, json=data)
print(response.json())
L0梯度最小化方法图像去雨代码
以下是使用L0梯度最小化方法进行图像去雨的Python代码,需要安装numpy和scipy库:
```python
import numpy as np
from scipy.signal import convolve2d
def L0_grad_minimization(image, lmda=2e-2, kappa=2.0):
# 将图像转换为灰度图
if len(image.shape) == 3:
image = np.mean(image, axis=2)
# 初始化参数
beta_max = 1e5
beta = 2*lmda
fx = np.array([-1, 1]).reshape((1, 2))
fy = np.array([-1, 1]).reshape((2, 1))
N, M = image.shape
h = np.zeros((N, M))
v = np.zeros((N, M))
beta_stop = 1e-3
# 计算DCT系数
dct = np.zeros((N, M))
dct[:N//8, :M//8] = 1
# 迭代优化
while beta < beta_max:
# 更新h和v
hdiff = np.hstack((np.diff(h, axis=1), np.zeros((N, 1))))
vdiff = np.vstack((np.diff(v, axis=0), np.zeros((1, M))))
norm = np.sqrt(hdiff**2 + vdiff**2)
t = 1/(norm/lmda + 1/beta)
h = t*np.maximum(0, hdiff + beta/lmda*(convolve2d(h, fx, mode='same') - v))
v = t*np.maximum(0, vdiff + beta/lmda*(convolve2d(v, fy, mode='same') - h))
# 更新beta
beta *= kappa
# 如果beta太小则停止
if beta < beta_stop:
break
# 计算图像去雨结果
d = dct * np.fft.fft2(h+v)
result = np.real(np.fft.ifft2(d))
return result
```
其中,`image`为输入图像,`lmda`为平滑因子,`kappa`为更新beta时的倍数增长因子。函数返回去雨后的图像。