1、读文件
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import csv csv_reader = csv.reader(open("data.file", encoding="utf-8"))for row in csv_reader: print(row) |
csv_reader把每一行数据转化成了一个list，list中每个元素是一个字符串。
2、写文件
读文件时，我们把csv文件读入列表中，写文件时会把列表中的元素写入到csv文件中。
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list = ["1", "2", "3", "4"]out = open(outfile, "w")csv_writer = csv.writer(out)csv_writer.writerow(list) |
可能遇到的问题：直接使用这种写法会导致文件每一行后面会多一个空行。
解决办法如下：
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out = open(outfile, "w", newline="")csv_writer = csv.writer(out, dialect="excel")csv_writer.writerow(list) |
在stackoverflow上找到了比较经典的解释，原来 python3里面对 str和bytes类型做了严格的区分，不像python2里面某些函数里可以混用。所以用python3来写wirterow时，打开文件不要用wb模式，只需要使用w模式，然后带上newline=''。
3、示例
- 简单读写
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import csv class writer: def __init__(self): self.dict = { "标题": "标题", "链接": "链接", "服务": "服务", "dsr": "dsr", "店铺名": "店铺名", "价格": "店铺名", "付款人数": "付款人数", "发货地": "发货地", } out = open("outfile.csv", "w", newline="") self.csv_writer = csv.writer(out, dialect="excel") self.csv_writer.writerow(self.dict) def writer_to(self, key_value): self.csv_writer.writerow(key_value) if __name__ == "__main__": a = writer() new = { "链接": "http://www.baidu.com", "标题": "我是标题", } a.dict.update(new) print(a.dict) a.writer_to(a.dict.values()) |
- 结合爬虫
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import csvfrom selenium import webdriverfrom selenium.webdriver.common.by import Byfrom selenium.webdriver.support.ui import WebDriverWaitfrom selenium.webdriver.support import expected_conditions as ECfrom selenium.common.exceptions import TimeoutException, NoSuchElementExceptionfrom selenium.webdriver.common.action_chains import ActionChains driver = ["1", "2"]colspan = ["1", "2"]try: out = open("类目.csv", "w", newline="")except PermissionError: print("文件被其他程序占用") input("")csv_writer = csv.writer(out, dialect="excel")csv_writer.writerow(["宝贝ID", "类目"]) def open_chrome(): driver[0] = webdriver.Chrome() driver[0].get("https://www.dianchacha.com") input("请登陆后按回车:") def EC_located(one_group, value): """ 目的：简化代码长度，参数1选择one或者group切换选中模式 :param value:要找的值【CSS选择器】 :return:选择到的对象 """ wait = WebDriverWait(driver[0], 10) if one_group == "one": try: ecl = wait.until(EC.presence_of_element_located((By.CSS_SELECTOR, value))) return ecl except TimeoutException: print(value, "1元素未加载成功，等待超时") else: try: ecl = wait.until( EC.presence_of_all_elements_located((By.CSS_SELECTOR, value)) ) return ecl except TimeoutException: print(value, "1元素---组---未加载成功，等待超时") def operating(ID): # 先获取ID输入框 driver[0].get("https://www.dianchacha.com/item/info/index/iid/" + ID) html = driver[0].page_source if "未能找到亲的宝贝" not in html: colspans = EC_located("group", ".colspan-1") colspan[0] = str(colspans[1].text).replace("宝贝类目： ", "") else: return operating(ID) print(colspan) def writer_txt(): csv_writer.writerow([url[0], colspan[0]]) print("保存", url[0], colspan[0], "成功") url = ["0", "1"] def main(): open_chrome() file = "宝贝ID.txt" with open(file) as f: for line in f.readlines(): url[0] = line print(line) operating(url[0]) writer_txt() out.close() print("已完成") if __name__ == "__main__": main() |
以上就是利用python 读写csv文件的详细内容，更多关于python 读写csv文件的资料请关注服务器之家其它相关文章！
原文链接：https://www.addcoder.com/blog/article_detail/0wx4ritl/
