csv文件是一种以逗号分割字符的文件形式
我们创建一个简单的文件demo.csv,如下格式的形式进行存储,以,进行分割
name,score,age,sex lhh,100,24,男 wcy,99,28,女
import pandas as pd # 读取csv文件 全文件读取 data = pd.read_csv('demo.csv',encoding="gbk") # 中文显示需要指定编码格式 df = pd.DataFrame(data) # 当然这一步也可以不要,因为读出来的结果就是这种格式的,但是习惯性的写上这种方式 print(df)
输出:
name score age sex 0 lhh 100 24 男 1 wcy 99 28 女
# 读取csv文件,一行一行的进行读取 file = pd.read_csv('demo.csv',encoding="gbk") df = pd.DataFrame(file) for i in range(len(df)): row = df[i:i+1] print(row ,'\n')
输出:
name score age sex 0 lhh 100 24 男 name score age sex 1 wcy 99 28 女
# row print("获取row 中的每个值") for i in range(len(df)): row = df[i:i+1] name = row ['name'][i] score = row ['score'][i] print(name,score,'\n')
# 写 使用pd将数据写入到csv文件当中,按列写入 file = pd.read_csv('demo.csv',encoding="gbk") df = pd.DataFrame(file) dict = {} for i in range(len(df)): row = df[i:i + 1] name = row['name'][i] sex = row['sex'][i] dict[name] = sex new_df = pd.DataFrame.from_dict(dict,orient='index') new_df.to_csv('demo_new.csv')
文件内容:
,0 lhh,男 wcy,女
#encoding=utf-8 import csv # 读取csv文件 with open("demo.csv","r",encoding="gbk") as csvfile: spamreader = csv.reader(csvfile) for row in spamreader: print(row)
输出:
['name', 'score', 'age', 'sex'] ['lhh', '100', '24', '男'] ['wcy', '99', '28', '女']
# 以字典的形式读取 with open("demo.csv","r",encoding="gbk") as file: reader = csv.DictReader(file) items = list(reader) print(items)
输出
[{'name': 'lhh', 'score': '100', 'age': '24', 'sex': '男'}, {'name': 'wcy', 'score': '99', 'age': '28', 'sex': '女'}]
#指定列读取 filename = ['name','sex'] with open("demo.csv","r",encoding="gbk") as file: reader = csv.DictReader(file,filename) items = list(reader) print(items)
输出:
[{'name': 'name', 'sex': 'score', None: ['age', 'sex']}, {'name': 'lhh', 'sex': '100', None: ['24', '男']}, {'name': 'wcy', 'sex': '99', None: ['28', '女']}]
# 写入csv文件 with open("demo_new_csv.csv","w") as file: writer = csv.writer(file) writer.writerow(['name','score']) # 此时的标题需要以list形式写入,writer会在新建的csv文件中,一行一行写入
文本内容
name,score
以字典方式写入
with open('demo_new_csv.csv', 'w',newline="",encoding="gbk") as f: writer = csv.DictWriter(f,fieldnames=["name","score","age","sex"]) writer.writeheader() writer.writerows(items) writer.writerow({'name': 'lhh', 'score': '100', 'age': '24', 'sex': '男'})
文本内容
name,score,age,sex lhh,100,24,男 wcy,99,28,女 lhh,100,24,男