一、pandas读取方式
1、csv介绍
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,sexlhh,100,24,男wcy,99,28,女
2.读文件
直接读取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 sex0 lhh 100 24 男1 wcy99 28 女
按行读取
# 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 sex0 lhh 100 24 男 name score age sex1 wcy99 28 女
获取文本标题中的每个值
# rowprint("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')
3.写入csv
# 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] = sexnew_df = pd.DataFrame.from_dict(dict,orient='index')new_df.to_csv('demo_new.csv')
文件内容:
,0lhh,男wcy,女
二、csv读取方式
1.读取操作
#encoding=utf-8import 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']
2.以字典形式进行读取
# 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']}]
3.写入操作
# 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,sexlhh,100,24,男wcy,99,28,女lhh,100,24,男