Tag Archives: Python
RMBS Prototype Model in Python
Posted by Shawn Zhang
on April 18, 2013
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Parameters
Parameters including : Total balance , Attach point, mortgage rate , Tranche Rate, Payment term and Prepayment CPR .
Cash Flow Chart result:
Full code(2 functions):
def rmbs_show(self):
self.clr_update_frame()
Label( self.update_frame, text="CPR" ).grid( row = 0, column= 0 )
w = Scale( self.update_frame, from_=0.01, to=0.20, resolution = 0.005, orient=HORIZONTAL, variable=self.rmbs_cpr, showvalue = True )
w.grid(row = Read more [...]
Conditional Checking in Python
Posted by Shawn Zhang
on March 22, 2013
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When story begins
In Python , there is a shortcut in conditional checking, I didn't take much care about the difference of below form of conditional syntax :
if var :
stmt;
if var is not None :
stmt;
if var != None:
stmt;
Explanation behind the scene is an analogy to difference of an empty string "" and NULL in a database . "" is an empty string but means something, NULL is nothing means nothing . In Python world , None equals NULL in Database , that's why "" == Read more [...]
Constraints on Arguments in Python
Posted by Shawn Zhang
on March 22, 2013
4 comments
When Dynamic Type comes to Trouble
As a dynamic programming languages , Python don't have a type on variables , as well as a arguments . This feature save us a lot workload and it enable us to focus on logical of program .
def add(x, y):
return x+y
print add(5,6)
>> 11
print add("D","E")
>> "DE"
print add(5.0, 6)
>> 11.0
Above function is straightforward and works fine if x and y are passed with int/ float/ string .
But things may Read more [...]
[译文]Decorators and Functional Python[draft]
Posted by Shawn Zhang
on January 16, 2013
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Original blog post wrote by Brian Holdefehr. This is a Chinese version of original post .
本文原文作者 Brian Holdefehr。若有不足，敬请斧正。
装饰器(Decorators) 是Python众多强大特性之一。装饰器除了本身编程语法上的作用之外，另外提供了一种有趣思维方式——"函数化"思维(a functional way)
我会从头开始介绍介绍装饰器的工作原理，接着会介绍几个必须了解的基本概念。之后，我们会详细深入探索一些装饰器实例以及其工作方式。最后我们会讨论一些装饰器的高阶应用，例如参数化装饰器(optional Read more [...]
Get Stock Quote Price API from Yahoo Finance via Python
Posted by Shawn Zhang
on December 28, 2012
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Difference against Google Finance / Sina.com
Yahoo provide more rich function regarding to the Stock API than Google / Sina.com does. particular ,it provide customize return format which customized by supply a parameter in calling URL . Full parameter specification pls refer to this link .(credit to Kelly Elias ) .
200 calls per second , you will be warned if you exceed this limits
csv file returned
No market depth as SIna.com provide
Provide stock indication such as " Earnings Read more [...]
Get Stock Quote from Goolge Web API via Python
Posted by Shawn Zhang
on December 27, 2012
No comments
Background
Google has officially announce that it won't sustain ongoing of Finance API, but there still a available API via URL API . Return data from web server is xml format . We need to parse the return text in Python and extract data .
Get the Stock Data
Google Web API format ( http://www.google.com/ig/api?stock=C ) , this will request market data for security code "C" ( Citigroup :) ) xml return result:
<xml_api_reply version="1">
<finance module_id="0" Read more [...]
Get Security Quote of Chinese Market from Sina.com via Python
Posted by Shawn Zhang
on December 27, 2012
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Intro
Although articles have been written about calling security quote API of Sina.com . I'd like to take a dive into it via Python and try to setup a OO implementation. Sina.com API will offer 5-th market depth prices of Chinese Shanghai / Shenzhen Exchange Stock in real time style .
API structure
calling Sina.com Stock API can be straightforward , just type "http://hq.sinajs.cn/list=sh601012" in browser address . call back will shown as below ( click to enlarge ):
Cracking Read more [...]
Project Euler Problem 26
Posted by Shawn Zhang
on December 23, 2012
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Question
A unit fraction contains 1 in the numerator. The decimal representation of the unit fractions with denominators 2 to 10 are given:
1/2
=
0.5
1/3
=
0.(3)
1/4
=
0.25
1/5
=
0.2
1/6
=
0.1(6)
1/7
=
0.(142857)
1/8
=
0.125
1/9
=
0.(1)
1/10
=
0.1
Where 0.1(6) means 0.166666..., and has a 1-digit recurring cycle. It can be seen that 1/7 has a 6-digit recurring cycle.
Find the value of d 
1000 for which 1/d contains Read more [...]
1000 for which 1/d contains Read more [...] Project Euler Question 14
Posted by Shawn Zhang
on December 20, 2012
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Question:
The following iterative sequence is defined for the set of positive integers:
n 
n/2 (n is even)
n 3n + 1 (n is odd)
Using the rule above and starting with 13, we generate the following sequence:
13 40 20 10 5 16 8 4 2 1
It can be seen that this sequence (starting at 13 and finishing Read more [...]
n/2 (n is even)
n 3n + 1 (n is odd)
Using the rule above and starting with 13, we generate the following sequence:
13 40 20 10 5 16 8 4 2 1
It can be seen that this sequence (starting at 13 and finishing Read more [...] Project Euler Question 29
Posted by Shawn Zhang
on December 19, 2012
No comments
Question:
Consider all integer combinations of ab for 2 
a 5 and 2 b 5:
22=4, 23=8, 24=16, 25=32
32=9, 33=27, 34=81, 35=243
42=16, 43=64, 44=256, 45=1024
52=25, 53=125, 54=625, 55=3125
If they are then placed in numerical order, with any repeats removed, we get the following sequence of 15 distinct terms:
4, 8, 9, 16, 25, 27, 32, 64, 81, 125, 243, 256, 625, 1024, 3125
How many distinct terms are in the sequence generated by ab for 2 a 100 Read more [...]
a 5 and 2 b 5:
22=4, 23=8, 24=16, 25=32
32=9, 33=27, 34=81, 35=243
42=16, 43=64, 44=256, 45=1024
52=25, 53=125, 54=625, 55=3125
If they are then placed in numerical order, with any repeats removed, we get the following sequence of 15 distinct terms:
4, 8, 9, 16, 25, 27, 32, 64, 81, 125, 243, 256, 625, 1024, 3125
How many distinct terms are in the sequence generated by ab for 2 a 100 Read more [...]