接下来实现一个top N查询,在top N语句中必定含有order by子句,即取最大或最小的N条记录;否则top N的结果将是不确定的。最直接的方法实现top N就是先根据where记录塞选记录,然后在根据order by属性排序,排序完毕后,取前N条记录输出即可。但这样效率比较低,如果N很小,而where子句的条件又不严格,满足条件的记录...
n, m = x_mat.shape print(“共有”, n, “个评价对象”, m, “个评价指标”) judge = int(input(“指标是否需要正向化处理,需要请输入1,不需要则输入0:”)) if judge == 1: position = np.array([int(i) for i in input(“请输入需要正向化处理的指标所在的列,例如第1、3、4列需要处理,...
"html.parser")print('豆瓣电影250: 序号 \t影片名\t 评分 \t评价人数')fortaginsoup.find_all(attrs={"class":"item"}):content=tag.get_text()content=content.replace('\n','')#删除多余换行print(content,'\n')#
2 import codecs 3 s ="———豆瓣电影top250———\r\n" 4 f = codecs.open("豆瓣电影top250.txt",'w','utf-8') 5 f.write(s) 6 7 for i in movieData250: 8 f.write(str(i)+'\r\n') #\r\n为换行符 9 f.close() 1. 2. 3. 4. 5. 6. 7. 8. 9. 源代码: 1 #豆瓣...
table+="| "+" | ".join(["---"]*len(header))+" |\n"# 生成数据行forrowindata:table+="| "+" | ".join(str(cell)forcellinrow)+" |\n"returntable 提取数据并保存为md文件 代码语言:javascript 代码运行次数:0 运行 AI代码解释
#python有6个字符,它的索引从0开始,最大为5#正向数字索引one_str ="python"print(one_str[5])#结果为:n#反向数字索引print(one_str[-3])#结果为:h#切片操作,只能取到结束索引的前一位print(one_str[2:4])#结果为:th 3、字符串的切片
sparse_dot_topnv1 is a significant change fromv0.*with a new bindings and API. The new version adds support for CPython 3.12 and now supports both ints as well as floats. Internally we switched to a max-heap to collect the top-n values which significantly reduces memory-footprint. The...
下面通过Python3代码可以获取电影的信息,调用BeautifulSoup中的find_all()函数获取< div class=’item’ >的信息,其结果如图4所示。 test01.py # -*- coding:utf-8 -*- # By:Eastmount CSDN importurllib.requestimport re from bs4 import BeautifulSoup ...
knn = KNeighborsClassifier(n_neighbors = 3) knn.fit(X_train, Y_train) Y_pred = knn.predict(X_test) acc_knn = round(knn.score(X_train, Y_train) * 100, 2) # Gaussian Naive Bayes gaussian = GaussianNB() gaussian.fit(X_train, Y_train) ...
Python爬虫:豆瓣电影 Top250,包括电影导演、类型、年份、 主演 结果输出到文本文件中。 1 import codecs 2 import requests 3 from bs4 import BeautifulSoup 4 5 headers={'User-Agent': 'Mozilla/5.0'} 6 index_url = 'https://movie.douban.com/top250' 7 8 def get_html(url): 9 html = requests...