Displaying Calculation Output of Python Script to Web Page using Python-based Web Server

It'll be convenient if we could displaying output from our Python code to web page.

To convert calculation output of Python script to web page we need BaseHTTPServer, a Python-based web server. With it, we could write any python code and display it in no time. It has advantage in form of simplicity, we don't need php to convert our result or typing it to static html code, we just used python alone (it's possible to write html and php code on python though).
This code below will display python script calculating value of a function (sin(x)+x^2) to web page. As it behave as web server too, we don't need apache or other web server to broadcast it.

Here the code. It's written in Python 2.7 on Mac OS X Lion with numpy module and sys, parser and basehttpserver built in module.

from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer
import sys,parser
from math import *
import numpy as np

class Handler(BaseHTTPRequestHandler):
    def do_GET(self):
        n=10
        x=7
        y = 'sin(x)+x**2'
        z = parser.expr(y).compile()
        
        self.send_response(200)
        self.send_header("Content-type", "text/html")
        self.end_headers()
        
        self.wfile.write("")
        self.wfile.write("")
        self.wfile.write("Hi Folks, Aravir here
")
        self.wfile.write("
")
        self.wfile.write("The value of ")
        self.wfile.write(y )
        self.wfile.write(" on x = " )
        self.wfile.write(x)
        self.wfile.write(" is " )
        self.wfile.write(eval(z) )

        self.wfile.write("")

if __name__=="__main__":
    try:
        server = HTTPServer(("", 8080), Handler)
        server.serve_forever()
    except KeyboardInterrupt:
        server.socket.close()

Access it using web browser in localhost:8080 from your computer running code above, or :8080 and get this

From python

Creating Web Page using Python including its Webserver (basehttpserver module)

It's possible to create web page using Python, even self hosted it using Python built in webserver (basehttpserver module)

Here the code. It'll create web server with port 8080 and if it's accessed, it'll show a page. In the code below, page showed for us is just plain text "magic content goes here". I am planning to investigate this self.wfile.write behavior.

from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer

class Handler(BaseHTTPRequestHandler):
    def do_GET(self):
        self.send_response(200)
        self.send_header("Content-type", "text/html")
        self.end_headers()
        
        self.wfile.write("magic content goes here")

if __name__=="__main__":
    try:
        server = HTTPServer(("", 8080), Handler)
        server.serve_forever()
    except KeyboardInterrupt:
        server.socket.close()

Access with browser in address localhost:8080 or <whatever your ip address>:8080 and get this

From python

Django ain't for This

While I'm searching for tutorial about creating simple static web page using Django, I surprised that i found almost nothing. There is Django documentation for it but I think it's too much; creating microblogger, forum, note, wiki, etc.

According what I found after surfed a while, Django isn't for this. I was suggestet to use basehttpserver instead.



Here what I found

"I have python scripts which provides output and I need to have this output on the web."


That is not what Django is for. What you want to do can be achieved with something as simple as this:

from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer

class Handler(BaseHTTPRequestHandler):
    def do_GET(self):
        self.send_response(200)
        self.send_header("Content-type", "text/html")
        self.end_headers()

        self.wfile.write("magic content goes here")

if __name__=="__main__":
    try:
        server = HTTPServer(("", 8080), Handler)
        server.serve_forever()
    except KeyboardInterrupt:
        server.socket.close()

Observe the self.wfile.write line. Whatever you write there ends up in the browser. If it matters, you can use self.path in the Handler to check which file was requested.

Tested with Python 2.6.4, accessed the server with Chrome browser.

..........

If you need a quick web server running and you don't want to mess with setting up apache or something similar, then Python can help. Python comes with a simple builtin HTTP server. With the help of this little HTTP server you can turn any directory in your system into your web server directory. The only thing you need to have installed is Python.

Practically speaking this is very useful to share files inside your local network. Implementing this tiny but hugely useful HTTP server is very simple, its just a single line command.

Assume that I would like to share my home directory
Open up a terminal and type:

$ cd 
$ python -m SimpleHTTPServer

That's it! Now your http server will start in port 8000. You will get the message:

Serving HTTP on 0.0.0.0 port 8000 ...

Now open a browser and type the computer address like:

http://192.168.1.1:8000

If you on computer that is running server, you can also access it via:

http://127.0.0.1:8000

If the directory has a file named index.html, that file will be served as the initial file. If there is no index.html, then the files in the directory will be listed.
If you wish to change the port that's used start the program via:

$ python -m SimpleHTTPServer 8080

If you want to only serve on localhost you'll need to write a custom Python program such as:

import sys
import BaseHTTPServer
from SimpleHTTPServer import SimpleHTTPRequestHandler

HandlerClass = SimpleHTTPRequestHandler
ServerClass  = BaseHTTPServer.HTTPServer
Protocol     = "HTTP/1.0"

if sys.argv[1:]:
    port = int(sys.argv[1])
else:
    port = 8000
server_address = ('127.0.0.1', port)

HandlerClass.protocol_version = Protocol
httpd = ServerClass(server_address, HandlerClass)

sa = httpd.socket.getsockname()
print "Serving HTTP on", sa[0], "port", sa[1], "..."
httpd.serve_forever()

Get a List of Link of a Website using Php

It'll be convenient if we could grab all link on a website just like firefox add-on--DownThemAll, and put it in our pages.

Fortunately, PHP has fopen function we could use for it. Here the code. It'll get this blog source, search for link, and print to screen the result.



<?php
$url = 'http://aravir-rose.blogspot.com';
$f = @fopen($url,"r");
while( $buf = fgets($f,1024) )
{
$buf = fgets($f, 4096);
preg_match_all("/<\s*a\s+[^>]*href\s*=\s*[\"']?([^\"' >]+)[\"' >]/isU",$buf,$words);
for( $i = 0; $words[$i]; $i++ )
{
for( $j = 0; $words[$i][$j]; $j++ )
{
$cur_word = strtolower($words[$i][$j]);
print "$cur_word<br>";
}
}
}
?>


Here the screenshot

From php

LLVM-GCC on OS X Lion

I confused about GCC version brought by XCode 4.2 on OS X Lion, so I surfing and landing on several sites to find out what is this llvm version.

Here some result.

Llvm stand for low level virtual machine



The LLVM Project (llvm.org) is a collection of modular and reusable compiler and toolchain technologies. Despite its name, LLVM has little to do with traditional virtual machines, though it does provide helpful libraries that can be used to build them.

The llvm-gcc command is the LLVM C front end. It is a modified version of gcc that compiles C/ObjC programs into native objects, LLVM bitcode or LLVM assembly language, depending upon the options.

By default, llvm-gcc compiles to native objects just like GCC does. If the -emit-llvm and -c options are given then it will generate LLVM bitcode files instead. If -emit-llvm and -S are given, then it will generate LLVM assembly.

Being derived from the GNU Compiler Collection, llvm-gcc has many of gcc's features and accepts most of gcc's options. It handles a number of gcc's extensions to the C programming language. See the gcc documentation for details.

Clang vs GCC (GNU Compiler Collection)

Clang ( /ˈklæŋ/)[2] is a compiler front end for the C, C++, Objective-C, and Objective-C++ programming languages. It uses the Low Level Virtual Machine (LLVM) as its back end, and Clang has been part of LLVM releases since LLVM 2.6.

Its goal is to offer a replacement to the GNU Compiler Collection (GCC). Development is sponsored by Apple. Clang is available under a free software license.

The Clang project includes the Clang front end and the Clang static analyzer among others.[3]

Pro's of GCC vs clang:

• GCC supports languages that clang does not aim to, such as Java, Ada, FORTRAN, etc.
• GCC has a few C++'11 features that Clang does not yet support.
• GCC supports more targets than LLVM.
• GCC is popular and widely adopted.
• GCC does not require a C++ compiler to build it.

Pro's of clang vs GCC:

• The Clang ASTs and design are intended to be easily understandable by anyone who is familiar with the languages involved and who has a basic understanding of how a compiler works. GCC has a very old codebase which presents a steep learning curve to new developers.
• Clang is designed as an API from its inception, allowing it to be reused by source analysis tools, refactoring, IDEs (etc) as well as for code generation. GCC is built as a monolithic static compiler, which makes it extremely difficult to use as an API and integrate into other tools. Further, its historic design and current policy makes it difficult to decouple the front-end from the rest of the compiler.
• Various GCC design decisions make it very difficult to reuse: its build system is difficult to modify, you can't link multiple targets into one binary, you can't link multiple front-ends into one binary, it uses a custom garbage collector, uses global variables extensively, is not reentrant or multi-threadable, etc. Clang has none of these problems.
• For every token, clang tracks information about where it was written and where it was ultimately expanded into if it was involved in a macro. GCC does not track information about macro instantiations when parsing source code. This makes it very difficult for source rewriting tools (e.g. for refactoring) to work in the presence of (even simple) macros.
• Clang does not implicitly simplify code as it parses it like GCC does. Doing so causes many problems for source analysis tools: as one simple example, if you write "x-x" in your source code, the GCC AST will contain "0", with no mention of 'x'. This is extremely bad for a refactoring tool that wants to rename 'x'.
• Clang can serialize its AST out to disk and read it back into another program, which is useful for whole program analysis. GCC does not have this. GCC's PCH mechanism (which is just a dump of the compiler memory image) is related, but is architecturally only able to read the dump back into the exact same executable as the one that produced it (it is not a structured format).
• Clang is much faster and uses far less memory than GCC.
• Clang aims to provide extremely clear and concise diagnostics (error and warning messages), and includes support for expressive diagnostics. GCC's warnings are sometimes acceptable, but are often confusing and it does not support expressive diagnostics. Clang also preserves typedefs in diagnostics consistently, showing macro expansions and many other features.
• GCC is licensed under the GPL license. clang uses a BSD license, which allows it to be used by projects that do not themselves want to be GPL.
• Clang inherits a number of features from its use of LLVM as a backend, including support for a bytecode representation for intermediate code, pluggable optimizers, link-time optimization support, Just-In-Time compilation, ability to link in multiple code generators, etc.
• Clang's support for C++ is more compliant than GCC's in many ways (e.g. conformant two phase name lookup).

From forum (http://www.cocos2d-iphone.org/forum/topic/7923)
"Have you experienced any incompatibility between LLVM compiler and GCC compiler ?


I found one strange issue:
If you compile ParticleTests with GCC and if you try sub-test "issue 872", it works as expected: a particle system will emit particles.
But if you compile it with LLVM 1.5, you won't see any particle at all. I'm not sure what's the problem, but I'll investigate it a bit further.


I can only reproduce this bug on the simulator. It seems that this bug can't be reproduced on the devices.


I tested it both in Release & Debug mode using Xcode 3.2.3"
............

"A developer at Apple (guy working on LLVM) highly suggested moving away from GCC immediately. He says Apple is no longer fixing bugs in GCC, and in XCode 4 GCC-LLVM will be the default option.


I've noticed sometimes LLVM will not compile against really old libraries compiled with GCC (gives errors about built in runtime functions not found). I can fix that by using GCC-LLVM (gcc parser, LLVM code generator).


A few days ago I noticed a bug in my code that only showed up when using LLVM (but not GCC). I tracked it down to a non initialized local variable that was being read from, and GCC would always initialize to zero (even with O3 optimizations). Since the variable value should be undefined, LLVM was giving the correct behavior of using whatever was in that memory already (even though it's clearly not the desired result). I'd speculate something similar is going on with ParticleTests.


I did a quick test, and compiling Cocos2D with GCC-LLVM works correctly with issue 872."

Robert Cross Edge Detection using Python on OS X Lion

The code below will convert an image to grayscale, get its pixel value and save it in array. With its pixel value in array, it's easy to apply Robert Cross Edge detect operation.

This operator is simpler than Sobel's.

print 'Program Python Deteksi Tepi'
print 'oleh Nugroho Adi Pramono'
'''Komentar diantara tiga-tanda petik tidak akan dibaca
oleh python'''
#komentar setelah tanda pagar juga tidak di baca oleh python
import Image        #memanggil modul untuk olah gambar
import os,sys       #memanggil modul untuk mengakses file
import numpy as np  #memanggil modul untuk operasi maatematika matrik/array
gb = Image.open('../gambar.jpg')                   #memasukkan gambar ke variabel gb
print 'format awal: ' ,gb.format, "%dx%d" % gb.size, gb.mode
print 'konversi ke grayscale'
gbw = gb.convert("L")
gbw.save('gambarBW.jpg')                #simpan hasil konversi ddg nama gambarBW.jpg
gbw = Image.open('gambarBW.jpg')        #masukkan gambar grayscale hasil konversi ke variabel gbw
print 'format: ',gbw.format, "%dx%d" % gbw.size, gbw.mode
ukuran=gbw.size                         #mengambil nilai resolusi gambar
'''buat array r dan s berukuran sama dengan ukuran gambar'''
r=np.zeros((ukuran[0],ukuran[1]),dtype=np.integer)
s=np.zeros((ukuran[0],ukuran[1]),dtype=np.integer)
print 'Mengambil nilai piksel, masukkan ke array r'
for i in range (ukuran[0]):
    for j in range (ukuran[1]):
        r[i,j]=gbw.getpixel((i,j))
print 'Deteksi tepi menggunakan operator Robert'
gx=np.zeros((ukuran[0],ukuran[1]),dtype=np.integer)
gy=np.zeros((ukuran[0],ukuran[1]),dtype=np.integer)
g=np.zeros((ukuran[0],ukuran[1]),dtype=np.float)
for i in range (ukuran[0]-1):
    for j in range (ukuran[1]-1):
        gx[i,j]=r[i,j]-r[i+1,j+1]
        gy[i,j]=r[i,j+1]-r[i+1,j]
g=np.sqrt(np.power(gx,2)+np.power(gy,2))
print 'Atur threshold'
for i in range (ukuran[0]-1):
    for j in range (ukuran[1]-1):
        if (g[i,j]<11):
            s[i,j]=0
        else:
            s[i,j]=255
            
print 'update gambar'
for i in range (ukuran[0]):
    for j in range (ukuran[1]):
        gbw.putpixel((i,j),s[i,j])      #letakkan pixel yang telah dimodifikasi ke posisi i,j
print 'Menyimpan gambar'
gbw.save('gambarRobert.jpg')          #simpan dengan nama gambarRobert.jpg
print 'Gambar tersimpan'
print 'Program Selesai'

Here, the result

Image source

From python

Gray-scaled image

From python

Edge-detected image

From python

Vertical Sobel Operator Manual Edge Detection using Python and PIL

This python code is used to detect the edge, of course, using Sobel Operator. The 'manual' word in this post title means I apply it manually as scipy python module has it capability. This code convert a jpeg image to grayscale and then detect its edge.



Here the code, I used vertical detection only as my horizontal code result is scrambling. I will update it as soon as all code success

print 'Program Python Deteksi Tepi'
print 'oleh Nugroho Adi Pramono'
'''Komentar diantara tiga-tanda petik tidak akan dibaca
oleh python'''
#komentar setelah tanda pagar juga tidak di baca oleh python
import Image        #memanggil modul untuk olah gambar
import os,sys       #memanggil modul untuk mengakses file
import numpy as np  #memanggil modul untuk operasi maatematika matrik/array
gb = Image.open('../gambar.jpg')                   #memasukkan gambar ke variabel gb
print 'format awal: ' ,gb.format, "%dx%d" % gb.size, gb.mode
print 'konversi ke grayscale'
gbw = gb.convert("L")
gbw.save('gambarBW.jpg')                #simpan hasil konversi ddg nama gambarBW.jpg
gbw = Image.open('gambarBW.jpg')        #masukkan gambar grayscale hasil konversi ke variabel gbw
print 'format: ',gbw.format, "%dx%d" % gbw.size, gbw.mode
ukuran=gbw.size                         #mengambil nilai resolusi gambar
'''buat array r dan s berukuran sama dengan ukuran gambar'''
r=np.zeros((ukuran[0],ukuran[1]),dtype=np.integer)
s=np.zeros((ukuran[0],ukuran[1]),dtype=np.integer)
print 'Mengambil nilai piksel, masukkan ke array r'
for i in range (ukuran[0]):
    for j in range (ukuran[1]):
        r[i,j]=gbw.getpixel((i,j))
print 'Deteksi tepi menggunakan operator Sobel'
gx=np.zeros((ukuran[0],ukuran[1]),dtype=np.integer)
gy=np.zeros((ukuran[0],ukuran[1]),dtype=np.integer)
g=np.zeros((ukuran[0],ukuran[1]),dtype=np.float)
for i in range (1,ukuran[0]-1):
    for j in range (1,ukuran[1]-1):
        gy[i,j]=r[i+1,j-1]+2*r[i+1,j]+r[i+1,j+1]-r[i-1,j-1]-2*r[i-1,j]-r[i-1,j+1]
print 'Atur threshold'
print 'update gambar Vertikal'
for i in range (ukuran[0]):
    for j in range (ukuran[1]):
        gbw.putpixel((i,j),np.abs(gy[i,j]))      #letakkan pixel yang telah dimodifikasi ke posisi i,j
print 'Menyimpan gambar Vertikal'
gbw.save('gambarSobelVertikal.jpg')          #simpan dengan nama gambarSobelVertikal.jpg
print 'Gambar tersimpan'
print 'Program Selesai'

And here the result

Image source

From python

Gray-scaled image

From python

Edge-detected image

From python