How to read a simple text file in python ?

Daidalos November 08, 2019


Example of how to read a simple text file in python:

Read a text file

Let's consider the following file iso_8859-1.txt. To read and close the file do:

f = open('iso_8859-1.txt', 'r')

f.closed

Get all the file content

To get all the file content a solution is to use f.read():

f = open('iso_8859-1.txt', 'r')
data = f.read()
f.close

and print the content using

print(data)

returns here:

The following are the graphical (non-control) characters defined by
ISO 8859-1 (1987).  Descriptions in words aren't all that helpful,
but they're the best we can do in text.  A graphics file illustrating
the character set should be available from the same archive as this
file.

Hex Description                 Hex Description

20  SPACE
21  EXCLAMATION MARK            A1  INVERTED EXCLAMATION MARK
22  QUOTATION MARK              A2  CENT SIGN
    ...
    ...
    ...
    ...

To go through the content line by line and get the line's index just use splitlines():

lines = data.splitlines()

for idx,line in enumerate(lines):
    print(idx,line)

returns

0 The following are the graphical (non-control) characters defined by
1 ISO 8859-1 (1987).  Descriptions in words aren't all that helpful,
2 but they're the best we can do in text.  A graphics file illustrating
3 the character set should be available from the same archive as this
4 file.
5 
6 Hex Description                 Hex Description
7 
8 20  SPACE
9 21  EXCLAMATION MARK            A1  INVERTED EXCLAMATION MARK
10 22  QUOTATION MARK              A2  CENT SIGN
11 23  NUMBER SIGN                 A3  POUND SIGN
    ...
    ...
    ...
    ...

Read a file line by line

Another method using "readline()":

print( 'line 1: ',  f.readline() )
print( 'line 2: ',  f.readline() )
print( 'line 3: ',  f.readline() )

Note: each just readline is used, it goes to the following line. To go back at the beginning of the file a solution is to use seek():

f.seek(0)

To get the number of line, a solution is to use a simple for loop:

NumberOfLine = 0
for line in f:
    print( line )
    NumberOfLine += 1

Read a data file

To read a data file there are multiples solutions:

References

Links Site
Page sur le site de python: "Input and Output" python doc
How to get line count cheaply in Python? stackoverflow
C'est quoi le ascii ? wikipedia

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