if time.isdigit()解释一下
时间: 2023-12-03 12:03:23 浏览: 31
`time.isdigit()`是一个字符串方法,用于判断字符串是否由纯数字组成。它会返回一个布尔值,如果字符串中的所有字符都是数字,则返回True;否则返回False。
例如,对于字符串"12345",`time.isdigit()`将返回True,因为它只包含数字字符。而对于字符串"12ab34",`time.isdigit()`将返回False,因为它包含了非数字字符。
相关问题
import os from datetime import datetime, timedelta import time delta = timedelta(days=2) now = datetime.now() delete_time = now - delta path = '/home/tomcat/tomcat-8.5.57-Portal/logs/backup' while True: for dirpath, dirnames, filenames in os.walk(path): for dirname in dirnames: if dirname[-8:].isdigit(): dir_time = datetime.strptime(dirname[-8:], '%Y%m%d') if dir_time < delete_time: for filename in os.listdir(os.path.join(dirpath, dirname)): os.remove(os.path.join(dirpath, dirname, filename)) os.rmdir(os.path.join(dirpath, dirname)) print('clean backup log')怎么结束循环
可以使用 `break` 关键字来结束循环。将 `while True` 改为一个条件语句,当满足条件时就跳出循环,例如:
```
import os
from datetime import datetime, timedelta
delta = timedelta(days=2)
now = datetime.now()
delete_time = now - delta
path = '/home/tomcat/tomcat-8.5.57-Portal/logs/backup'
while condition:
for dirpath, dirnames, filenames in os.walk(path):
for dirname in dirnames:
if dirname[-8:].isdigit():
dir_time = datetime.strptime(dirname[-8:], '%Y%m%d')
if dir_time < delete_time:
for filename in os.listdir(os.path.join(dirpath, dirname)):
os.remove(os.path.join(dirpath, dirname, filename))
os.rmdir(os.path.join(dirpath, dirname))
print('clean backup log')
break # 跳出循环
```
你需要将 `condition` 替换为跳出循环的条件。
import time import csv import pandas as pd from selenium import webdriver from selenium.webdriver import Chrome,ChromeOptions from selenium.webdriver.common.by import By # driver_path = r'C:\Program Files\Google\Chrome\Application\chrome.exe' driver = webdriver.Chrome() driver.get('https://www.jd.com/') def drop_down(): for x in range(1,9,2): time.sleep(1) j = x /9 js = 'document.documentElement.scrollTop = document.documentElement.scrollHeight * %f' % j driver.execute_script(js) driver.find_element(By.CSS_SELECTOR,'#key').send_keys('燕麦') driver.find_element(By.CSS_SELECTOR,'.button').click() f = open(f'B:\京东商品数据.csv', mode='a', encoding='gbk', newline='') csv_writer = csv.DictWriter(f, fieldnames=[ '商品标题', '商品价格', '店铺名字', '标签', '商品详情页', ]) csv_writer.writeheader() 商品信息 = [] def get_shop(): time.sleep(10) # driver.implicitly_wait(10) drop_down() lis = driver.find_elements(By.CSS_SELECTOR,'#J_goodsList ul li') for li in lis: title = li.find_element(By.CSS_SELECTOR,'.p-name em').text.replace('\n', '') price = li.find_element(By.CSS_SELECTOR,'.p-price strong i').text shop_name = li.find_element(By.CSS_SELECTOR,'.J_im_icon a').text href = li.find_element(By.CSS_SELECTOR,'.p-img a').get_attribute('href') icons = li.find_elements(By.CSS_SELECTOR,'.p-icons i') icon = ','.join([i.text for i in icons]) dit = { '商品标题':title, '商品价格':price, '店铺名字':shop_name, '标签':icon, '商品详情页':href, } csv_writer.writerow(dit) # print(title,price,href,icon,sep=' | ') for page in range(1,3): time.sleep(1) drop_down() get_shop() driver.find_element(By.CSS_SELECTOR,'.pn-next').click() driver.quit() # data = csv.reader(open('B:\京东商品数据.csv'),delimiter=',') # sortedl = sorted(data,key=lambda x:(x[0],x[1]),reverse=True) # print('最贵的商品信息') # print(sortedl) # with open('B:\京东商品数据.csv','r',encoding='gbk') as f: # f_csv = csv.reader(f) # max_price = 0 # next(f_csv) # for row in f_csv: # if row[1].isdigit() and int(row[1]) > max_price: # max_price = int(row[1]) # print(max_price) with open('B:\京东商品数据.csv', 'r') as file: reader = csv.reader(file) header =next(reader) next(reader) max_price = float('-inf') for row in reader: num = float(row[1]) if num > max_price: max_price = num item = row[0] name_0= row[2] print(item,max_price,name_0)程序中出现ValueError: could not convert string to float: '商品价格'解决方法
在这个程序中,您使用了csv模块来读取和写入CSV文件,但是当您尝试将字符串转换为浮点数时出现了ValueError。这是因为您尝试将一个非数字字符串('商品价格')转换为float类型。
要解决这个问题,您需要在读取文件之前跳过CSV文件的第一行(即标题行),该行包含列名。可以使用csv.reader()函数的next()方法来跳过标题行,例如:
```
with open('B:\京东商品数据.csv', 'r') as file:
reader = csv.reader(file)
header = next(reader) # 跳过标题行
max_price = float('-inf')
for row in reader:
num = float(row[1])
if num > max_price:
max_price = num
item = row[0]
name_0= row[2]
print(item, max_price, name_0)
```
注意,这里使用float('-inf')来初始化max_price,以确保第一个价格将始终大于它。还要注意,您需要在for循环中保存商品名称和店铺名称,以便在找到最大价格时打印它们。
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