Detailed Explanation of python File Processing

Directory file operation 1. txt file open file 2. Data dimension 3. Excel file summary

File operation

This is my notes in the process of learning python, which will be updated continuously. Please ask questions and correct me.

1. txt file

1. Text file txt

2.2 Binary files, pictures and videos

Operation Flow Open-Operation-Close

Open a file

Variable name = open (file path and file name, schema)
Operation file
Variable name. close

Path uses\\ or/

模式	描述
r	只读
w	覆盖写，
x	创建写,创建文件
a	追加写
b	2进制文件模式
t	文本文件模式
+	与r/w/x/a1同使用

There is a problem in the writing position in the test, which only appeared once. I don't know if it is the problem of my operation. I hope to know the big brother can give directions under 1

f=open("G:\\Python\\txt.txt","a")
f=open("G:\\Python\\txt.txt","r+")
print(f.read())
f.write("99999999")
f.close()

# File reading is only the first 1 It will be called next time, and it will not take effect later 
# Measured a+ Unable to read file, r+ Cursor appears at the beginning in mode 1 Times 
read(10)   Read 10 Characters 
readline()  Read the 1 Row, before reading the row with parameters n Characters 
readlines()  Read all rows, and if there are parameters, read the n Row 

seek ( 0 )   Change the pointer position, 0 For the beginning, 1 For the end 
write () Writes content to file 
writelines () Joins all elements of a list type and writes them to a document 

2. Data dimension

1.1 Dimensional data

It is composed of ordered and unordered data of peer-to-peer relationship

2.2 Dimensional data

Also known as tabular data, it is organized in a two-dimensional tabular way, corresponding to the matrix in mathematics

3. High-dimensional data

It is composed of key-value pair type data, organized by object mode, and can be nested in multiple layers

High-dimensional data is common in web, and is the main way of organizing content in internet, including HTML, XML, JSON and so on

HTML: Available on Web page F12

XML: Android Studio

JSON: https://daily.zhihu.com/

​ https://news-at.zhihu.com/api/3/stories/latest

1-bit data

It is mainly stored in the form of list in python

The general idea is to use special characters to separate elements, such as spaces, commas, line breaks, and other special separators

ls=['1','2','3']
f.write(",".jion(ls))
join()   Connecting elements in a sequence with specified characters generates a new string 
print(",".jion(ls))

csv File Comma Separated Values

A generic, relatively simple file format with a suffix of. csv

After 1-bit data is saved, the elements are separated by commas (English commas), which is widely used in business and science

f=open("12.csv","r")
ls=f.read()
ls_new=ls.split(',')
# Slice the string by specifying the delimiter and return the list 
f.close

2D data

csv files can also store 2-dimensional data

ls=[["1","2"],
    ["3",["4"]]]
f=open("12.csv","w")
for row in ls:
    f.write(",".join(row)+"\n")
f.close



f = open("12.csv", "r")
ls = []
for line in f:
    ls.append(line.strip('\n').split(","))

    # a=line.strip('\n')
    # b=a.split(',')
    # ls.append(b) 
f.close

3. Excel file

# Introduce Excel Library xlrd   1.20 Version 
import xlrd

#  Open the one we just wrote  test_w.xls  Documents 
wb = xlrd.open_workbook(r'E:\MATLAB\project\shiyan\12.xlsx')
#  Get and print  sheet  Quantity 
print( "sheet  Quantity :", wb.nsheets)
#  Get and print  sheet  Name 
print( "sheet  Name :", wb.sheet_names())
#  According to  sheet  Index to get content 
sh1 = wb.sheet_by_index(0)
#  It can also be based on  sheet  Name get content 
sh = wb.sheet_by_name(' Achievement ')
#  Gets and prints the  sheet  Number of rows and columns 
print( u"sheet %s  Altogether  %d  Row  %d  Column " % (sh1.name, sh1.nrows, sh1.ncols))
#  Gets and prints the value of a cell 
print( " No. 1 1 Line number 2 The value of the column is :", sh1.cell_value(0, 1))
#  Gets the value of an entire row or column 
rows = sh1.row_values(0) #  Get the 1 Line content 
cols = sh1.col_values(1) #  Get the 2 Column content 
#  Print the obtained column and column values 
 print( " No. 1 1 The value of the row is :", rows)
print( " No. 1 2 The value of the column is :", cols)
#  Gets the data type of the cell content 
 print( " No. 1 2 Line number 1 The value type of the column is :", sh1.cell(1, 0).ctype)ets()[0]

Summarize

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