Python-based File Operation

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A Python-based File Operation is a file operation that is a Python operation.



References

2014

  • http://en.wikibooks.org/wiki/Python_Programming/Files
    • Files, specifically file handles, are an important example of resources, and thus should generally be managed using the with statement; see context managers section.

      In rare cases – namely when a file is not only used within a single block of code – it is necessary to do manual resource management using File.close(), but this is error-prone and requires great care to be exception safe. In interactive use using explicit open() and File.close() results in immediate evaluation, instead of the delayed evaluation of using a with statement.


Examples

Reading & Writing Files

Just reading from a file

 open my $io, “<-" or die "NO STDIN: $!" ;

Mixed Read & Write

...
Subroutine-based

Subroutine to open a file for writing and write into it.

import csv
filename = sys.argv[1]
with open(filename, 'rb') if sys.argv[1] is not "-" else sys.stdin as f:
   reader = csv.reader(f,dialect="excel-tab")  # creates the reader object
   for row in reader:
      ...

Subroutine to open a file for writing and write into it.

...
File Open Codes
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File Management

Rename a File

...

Delete a file

...

Choose between STDIN or file

...

Directory-based operations

Read a directory's files (shortcut with pattern matching).

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Load all files in a directory into the @files array

...

a subroutine approach

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JSON-based operations
import json

with open("data_file.json", "w") as write_file:
    json.dump(data, write_file)

print(json.dumps({'4': 5, '6': 7}, sort_keys=True, indent=4))
 {
    "4": 5,
    "6": 7
 }

...