Use Python to Create a Tree View Command Line Tool

In recent days I need to generate a directory free from the window command prompt. As I known there is a DOS tool called tree could do this. But it is not quite fit for my requirement. Here is an example which the graphic generated by built-in tree command in window.

D:\PersonalTools>tree D:\emacs-24.5 /A
卷 WareHouse 的文件夹 PATH 列表
卷序列号为 64CA-A0C3

D:\EMACS-24.5
+—admin
|   +—charsets
|   |   \—mapfiles
|   +—coccinelle
|   +—grammars
|   +—notes
|   +—nt
|   \—unidata
+—build-aux
|   \—snippet
+—doc
|   +—emacs
|   +—lispintro
|   +—lispref
|   +—man
|   \—misc
+—etc
|   +—charsets
|   +—e
|   +—forms
|   +—gnus
|   +—images
|   |   +—custom
|   |   +—ezimage
|   |   +—gnus
|   |   +—gud
|   |   +—icons
|   |   |   +—allout-widgets
|   |   |   |   +—dark-bg
|   |   |   |   \—light-bg
|   |   |   \—hicolor
|   |   |       +—128×128
|   |   |       |   \—apps
|   |   |       +—16×16
|   |   |       |   \—apps
|   |   |       +—24×24
|   |   |       |   \—apps
|   |   |       +—32×32
|   |   |       |   \—apps
|   |   |       +—48×48
|   |   |       |   \—apps
|   |   |       \—scalable
|   |   |           +—apps
|   |   |           \—mimetypes
|   |   +—low-color
|   |   +—mail
|   |   +—mpc
|   |   +—newsticker
|   |   +—smilies
|   |   |   +—grayscale
|   |   |   \—medium
|   |   \—tree-widget
|   |       +—default
|   |       \—folder
|   +—nxml
|   +—org
|   +—refcards
|   +—schema
|   +—srecode
|   +—themes
|   \—tutorials
+—info
+—leim
|   +—CXTERM-DIC
|   +—MISC-DIC
|   \—SKK-DIC
+—lib
+—lib-src
+—lisp
|   +—calc
|   +—calendar
|   +—cedet
|   |   +—ede
|   |   +—semantic
|   |   |   +—analyze
|   |   |   +—bovine
|   |   |   +—decorate
|   |   |   +—symref
|   |   |   \—wisent
|   |   \—srecode
|   +—emacs-lisp
|   +—emacs-parallel
|   +—emulation
|   +—erc
|   +—eshell
|   +—gnus
|   +—international
|   +—language
|   +—leim
|   |   +—ja-dic
|   |   \—quail
|   +—mail
|   +—mh-e
|   +—net
|   +—nxml
|   +—obsolete
|   +—org
|   +—play
|   +—progmodes
|   +—term
|   +—textmodes
|   +—url
|   \—vc
+—lwlib
+—m4
+—msdos
+—nextstep
|   +—Cocoa
|   |   \—Emacs.base
|   |       \—Contents
|   |           \—Resources
|   +—GNUstep
|   |   \—Emacs.base
|   |       \—Resources
|   \—templates
+—nt
|   +—icons
|   \—inc
|       +—arpa
|       +—netinet
|       \—sys
+—oldXMenu
+—site-lisp
\—src
\—bitmaps

A quite complicate file structure for emacs 24.5. There are several limitations for this command.

  1. It can’t control the iteration depth
  2. When display with files it doesn’t generated the dash lines which is not clearly to indicate the file structure
  3. If we could give a depth parameter I also want to display the sub items as ellipsis to indicate there is something under but which is omitted

So I use python to write a custom version to enhance this command called treex. It support generated the same structure as the tree command but also provide additional control switch. The source code is already pushed to my personal repository in GitHub. Feel free to check it out.

The help information is

usage: treex.py [-h] [-f] [-d DEPTH] [-m] [-e] path

A Cmd Line Tool for Graphically displays the folder structure of a drive or
path

positional arguments:
path

optional arguments:
-h, –help            show this help message and exit
-f, –file            Display the names of the files in each folder
-d DEPTH, –depth DEPTH
Display the depth number
-m, –mark            Mark the item is file or directory
-e, –ellipsis        Mark the next sub-item with ellipsis

Create by Edwin, Shang(Shang, Erxin) License under MIT. Version 1.0.0

Try to use the treex to generate a depth 2 directory structure

D:\PersonalTools>c:\Python27\python.exe treex.py D:\emacs-24.5 -d 2
Folder path listing
D:\emacs-24.5
+—admin
|   +—charsets
|   +—coccinelle
|   +—grammars
|   +—notes
|   +—nt
|   \—unidata
+—build-aux
|   \—snippet
+—doc
|   +—emacs
|   +—lispintro
|   +—lispref
|   +—man
|   \—misc
+—etc
|   +—charsets
|   +—e
|   +—forms
|   +—gnus
|   +—images
|   +—nxml
|   +—org
|   +—refcards
|   +—schema
|   +—srecode
|   +—themes
|   \—tutorials
+—info
+—leim
|   +—CXTERM-DIC
|   +—MISC-DIC
|   \—SKK-DIC
+—lib
+—lib-src
+—lisp
|   +—calc
|   +—calendar
|   +—cedet
|   +—emacs-lisp
|   +—emacs-parallel
|   +—emulation
|   +—erc
|   +—eshell
|   +—gnus
|   +—international
|   +—language
|   +—leim
|   +—mail
|   +—mh-e
|   +—net
|   +—nxml
|   +—obsolete
|   +—org
|   +—play
|   +—progmodes
|   +—term
|   +—textmodes
|   +—url
|   \—vc
+—lwlib
+—m4
+—msdos
+—nextstep
|   +—Cocoa
|   +—GNUstep
|   \—templates
+—nt
|   +—icons
|   \—inc
+—oldXMenu
+—site-lisp
\—src
\—bitmaps

Here is another result for generate with ellipsis and marks

D:\PersonalTools>c:\Python27\python.exe treex.py D:\emacs-24.5 -d 2 -e -m
Folder path listing
D:\emacs-24.5
[d]+—admin
[d]|   +—charsets
[d]|   |   \—…
[d]|   +—coccinelle
[d]|   +—grammars
[d]|   +—notes
[d]|   +—nt
[d]|   \—unidata
[d]+—build-aux
[d]|   \—snippet
[d]+—doc
[d]|   +—emacs
[d]|   +—lispintro
[d]|   +—lispref
[d]|   +—man
[d]|   \—misc
[d]+—etc
[d]|   +—charsets
[d]|   +—e
[d]|   +—forms
[d]|   +—gnus
[d]|   +—images
[d]|   |   +—…
[d]|   +—nxml
[d]|   +—org
[d]|   +—refcards
[d]|   +—schema
[d]|   +—srecode
[d]|   +—themes
[d]|   \—tutorials
[d]+—info
[d]+—leim
[d]|   +—CXTERM-DIC
[d]|   +—MISC-DIC
[d]|   \—SKK-DIC
[d]+—lib
[d]+—lib-src
[d]+—lisp
[d]|   +—calc
[d]|   +—calendar
[d]|   +—cedet
[d]|   |   +—…
[d]|   +—emacs-lisp
[d]|   +—emacs-parallel
[d]|   +—emulation
[d]|   +—erc
[d]|   +—eshell
[d]|   +—gnus
[d]|   +—international
[d]|   +—language
[d]|   +—leim
[d]|   |   +—…
[d]|   +—mail
[d]|   +—mh-e
[d]|   +—net
[d]|   +—nxml
[d]|   +—obsolete
[d]|   +—org
[d]|   +—play
[d]|   +—progmodes
[d]|   +—term
[d]|   +—textmodes
[d]|   +—url
[d]|   \—vc
[d]+—lwlib
[d]+—m4
[d]+—msdos
[d]+—nextstep
[d]|   +—Cocoa
[d]|   |   \—…
[d]|   +—GNUstep
[d]|   |   \—…
[d]|   \—templates
[d]+—nt
[d]|   +—icons
[d]|   \—inc
[d]|       +—…
[d]+—oldXMenu
[d]+—site-lisp
[d]\—src
[d]    \—bitmaps

The key technical point is the depth first traversal algorithms, and I implement it with nonrecursive mode to reduce the stack usage.

The other key point is how to generate the graphic. There is a pattern between the second line and the previous line. So I use it. The implementation could be found from the source.

That’s all. Happy coding.

 

Python基础教程,第一章 简介(Python Fundamental, Charpter 01 Introduction)

对Python编程语言做了基本的介绍
Make a basic introduction about python programming language.

主要内容:

  • Python的简介, introduction
  • Python的哲学, philosophy
  • Python的排名, current state
  • Python开发的项目, projects
  • Python的编程风格, programming style
  • Python的协议, license
  • Python的开发工具, development environment
  • Get required lasts lines from a huge text file in python

    During my work, I need to parse the result from some huge log files. The result is always save at the end of the file. So I need find a way to get the required last lines to accelerate the parse speed. Here is the function I have written to achieve this requirement in python.

    1. def last_lines(filename, lines=1):
    2. '''
    3. return the last lines from the specify files
    4. '''
    5. with open(filename, 'rb') as fh:
    6. fh.seek(0, os.SEEK_END)
    7. if fh.tell() == 0:
    8. return []
    9. fh.seek(-2, os.SEEK_END)
    10. #while not BOF
    11. while fh.tell() > 0:
    12. cur_char = fh.read(1).decode()
    13. if cur_char == '\n':
    14. lines -= 1
    15. if lines > 0:
    16. fh.seek(-2, os.SEEK_CUR)
    17. else:
    18. break
    19. return [line.decode() for line in fh.readlines()]

     

    Use oscilloscope Check the AC noise of a Power Source

    How to use a oscilloscope display the wave shape of AC power source?
    1. Check the oscilloscope is connected with attenuator probes, and adjust to the right attenuation factor. 1x, 10x 100x, … the more big the number the more attenuator value

    2. Adjust the oscilloscope to the relative measure scope and set to the right channel

    3. Connect the ground with the clamp to the ground of the source
    10092166

    4. Use one probe connecting with zero line, the other connected with the supply line

    5. Adjust the sample time to make the wave shape looks better

    6. The noise pulses are displayed during my measurement result

    WP_20141212_14_13_43_Pro

    WP_20141212_14_10_58_Pro