### 1.說明 CSV，全稱叫做Comma-Separated Values，即逗號分隔符或字符分隔符 ### 2.寫入 通過open\(\)方法寫入并創建一個csv文件，調用csv庫的writer\(\)方法初始化一個寫入對象，傳入該語柄，然后調用writerow\(\)方法傳入每行的數據即可完成寫入 ``` import csv with open('data.csv', 'w',newline='') as csvfile: writer = csv.writer(csvfile) writer.writerow(['id', 'name']) writer.writerow(['10001', '米庫']) ``` 注意:如果不帶newline=‘’，會發現也能寫入結果，但是每行內容之間總是會多出一個空行 如果想修改列與列之間的分隔符可以傳入delimiter參數 ``` import csv with open('data.csv', 'w',newline='') as csvfile: writer = csv.writer(csvfile,delimiter='0') writer.writerow(['id', 'name']) writer.writerow(['10001', '米庫']) ``` 默認的分隔符逗號\(,\)會被換成delimeter參數設置的分隔符 可以同時傳入多行，需要使用witerrows\(\)方法 注意:是writerrows而不是writerow ``` import csv with open('data.csv', 'w',newline='') as csvfile: writer = csv.writer(csvfile) writer.writerow(['id', 'name']) writer.writerows([['10001', '米庫'],['10001', '米庫'],['10001', '米庫']]) ``` 以字典的形式寫入csv文件 ``` import csv with open('data.csv', 'w',newline='') as csvfile: # 預先定義字段 fieldnames = ['id','name'] # 初始化一個字典寫入對象 writer = csv.DictWriter(csvfile, fieldnames=fieldnames) # 調用writeheader()方法先寫入頭信息 writer.writeheader() # 調用writerow傳入相應字典 writer.writerow({'id':1,"name":"angle"}) ``` 追加csv文本內容 注意這里就不同調用writeheader\(\)方法，不然會將頭部信息一并寫入 ``` import csv with open('data.csv', 'a',newline='') as csvfile: # 預先定義字段 fieldnames = ['id','name'] # 初始化一個字典寫入對象 writer = csv.DictWriter(csvfile, fieldnames=fieldnames) # 調用writerow傳入相應字典 writer.writerow({'id':1,"name":"angle"}) ``` 若將中文寫入csv文件中，需要指定編碼格式 ``` import csv with open('data.csv', 'a',newline=''，encoding='utf-8') as csvfile: # 預先定義字段 fieldnames = ['id','name'] # 初始化一個字典寫入對象 writer = csv.DictWriter(csvfile, fieldnames=fieldnames) # 調用writerow傳入相應字典 writer.writerow({'id':1,"name":"angle"}) ``` 利用pandas庫寫入csv文件 注意，字典的鍵值對中值的類型是列表形式 ``` import pandas as pd data = { 'name':["angle"], "age":[18], } print(data) df = pd.DataFrame(data) # print(df) df.to_csv('csv1.csv') ``` ### 3.讀取 ``` import csv with open('data.csv','r',encoding='utf-8') as csvfile: reader = csv.reader(csvfile) for content in reader: print(content) ``` 運行結果: ``` ['id', 'name'] ['1', 'angle'] ['id', 'name'] ['1', 'angle'] ['id', 'name'] ``` 利用pandas中read\_csv\(\)方法將數據從csv中讀取出來 ``` import csv with open('data.csv', 'w',newline='',encoding='utf-8') as csvfile: writer = csv.writer(csvfile) writer.writerow(['id', 'name']) writer.writerows([['10001', '米庫'],['10001', '米庫'],['10001', '米庫']]) # 用pandas讀取csv文本內容，需要寫入csv文本后時指定編碼格式utf-8 import pandas as pd print(pd.read_csv('data.csv')) ``` 運行結果: ``` id name 0 10001 米庫 1 10001 米庫 2 10001 米庫 ```