1.2.6. Input and Output

To be exhaustive, here are some information about input and output in Python. Since we will use the Numpy methods to read and write files, you may skip this chapter at first reading.

We write or read strings to/from files (other types must be converted to strings). To write in a file:

>>> f = open('workfile', 'w') # opens the workfile file
>>> type(f)    
<type 'file'>
>>> f.write('This is a test \nand another test')   
>>> f.close()

To read from a file

In [1]: f = open('workfile', 'r')

In [2]: s = f.read()

In [3]: print(s)
This is a test
and another test

In [4]: f.close()

See also

For more details: https://docs.python.org/tutorial/inputoutput.html

1.2.6.1. Iterating over a file

In [6]: f = open('workfile', 'r')

In [7]: for line in f:
   ...:     print(line)
   ...:
This is a test

and another test

In [8]: f.close()

File modes

• Read-only: r
• Write-only: w
  • Note: Create a new file or overwrite existing file.
• Append a file: a
• Read and Write: r+
• Binary mode: b
  • Note: Use for binary files, especially on Windows.