Python external Data read and write (Cvs,excel)

Python external Data Read and write

A practical Guide to Python Data science from Ji Lu

Csv

• What is CSV?
  Comma-separated values (comma-separated values,csv, sometimes also called character-delimited values, because delimited characters can also be not commas)
• CSV file read (str)

import csvwith open("D:/课件/《python数据科学》/data_science_tool_book_code/chapter7/test.csv") as fr:    rows = csv.reader(fr)    for row in rows:    #这里要缩进,rows相当于一个流，必须在文件开启时使用        print(row)        ######################[‘PassengerId‘, ‘Pclass‘, ‘Name‘, ‘Sex‘, ‘Age‘, ‘SibSp‘, ‘Parch‘, ‘Ticket‘, ‘Fare‘, ‘Cabin‘, ‘Embarked‘][‘892‘, ‘3‘, ‘Kelly, Mr. James‘, ‘male‘, ‘34.5‘, ‘0‘, ‘0‘, ‘330911‘, ‘7.8292‘, ‘‘, ‘Q‘][‘893‘, ‘3‘, ‘Wilkes, Mrs. James (Ellen Needs)‘, ‘female‘, ‘47‘, ‘1‘, ‘0‘, ‘363272‘, ‘7‘, ‘‘, ‘S‘][‘894‘, ‘2‘, ‘Myles, Mr. Thomas Francis‘, ‘male‘, ‘62‘, ‘0‘, ‘0‘, ‘240276‘, ‘9.6875‘, ‘‘, ‘Q‘][‘895‘, ‘3‘, ‘Wirz, Mr. Albert‘, ‘male‘, ‘27‘, ‘0‘, ‘0‘, ‘315154‘, ‘8.6625‘, ‘‘, ‘S‘][‘896‘, ‘3‘, ‘Hirvonen, Mrs. Alexander (Helga E Lindqvist)‘, ‘female‘, ‘22‘, ‘1‘, ‘1‘, ‘3101298‘, ‘12.2875‘, ‘‘, ‘S‘][‘897‘, ‘3‘, ‘Svensson, Mr. Johan Cervin‘, ‘male‘, ‘14‘, ‘0‘, ‘0‘, ‘7538‘, ‘9.225‘, ‘‘, ‘S‘]

• CSV file read (dictionary)

import csvwith open(‘D:/课件/《python数据科学》/data_science_tool_book_code/chapter7/test.csv‘) as fr:    rows=csv.DictReader(fr)    for row in rows:        print(row)

• CSV file Write

import csvwith open(‘./csv_tutorial.csv‘,‘a‘) as fw:    writer=csv.writer(fw)    writer.writerow([‘c1‘,‘c2‘,‘c3‘])   #同样,必须缩进

Excel

• Pandas
  A powerful data processing library that includes the processing of Excel formats
• Read Excel:

import pandas as pdfrom pandas import read_excelpd.set_option(‘display.max_columns‘,4)pd.set_option(‘display.max_rows‘,6)df= read_excel(‘D:/课件/《python数据科学》/data_science_tool_book_code/chapter8/A0202.xls‘,‘Sheet1‘)print(df)

• Write Excel

import pandas as pdfrom pandas import DataFramedf=DataFrame([[1,2,3,4],[5,6,7,8],[9,10,11,12]],index=[0,1,2],columns=list("ABCD"))df.to_excel(‘test.xls‘)

Read and write Python external data (Cvs,excel)