Implemeting Data Structures and Algorithms in Python: Problems and solutions

Recently I have started using Python in a lot of places including writing algorithms for MI/data science,  so I thought to try to implement some common programming problems using data structures in Python. As I have mostly implemented in C/C++ and Perl.

Let’s get started with a very basic problem.

Anagram algorithm

An algorithm will take two strings and check to see if they are anagrams. An anagram is when the two strings can be written using the exact same letters, in other words, rearranging the letters of a word or phrase to produce a new word or phrase, using all the original letters exactly once

Some examples of anagram:
“dormitory” is an anagram of “dirty room”
“a perfectionist” is an anagram of “I often practice.”
“action man” is an anagram of “cannot aim”

Our anagram check algorithm with take two strings and will give a boolean TRUE/FALSE depends on anagram found or not?
I have used two approaches to solve the problem. First is to sorted function and compare two string after removing white spaces and changing to lower case. This is straightforward.

like


def anagram(str1,str2):
# First we'll remove white spaces and also convert string to lower case letters
str1 = str1.replace(' ','').lower()
str2 = str2.replace(' ','').lower()
# We'll show output in the form of boolean TRUE/FALSE for the sorted match hence return
return sorted(str1) == sorted(str2)

The second approach is to do things manually, this is because to learn more about making logic to check. In this approach, I have used a counting mechanism and Python dictionary to store the count letter. Though one can use inbuilt Python collections idea is to learn a bit about the hash table.

Check GitHub for the full working code.

I will keep adding more problems/solutions.

Stay tuned!

Ref:  The inspiration of implementing DS in Python is from this course

Choropleth Maps in Python

Choropleth maps are a great way to represent geographical data. I have done a basic implementation of two different data sets. I have used jupyter notebook to show the plots.

World Power Consumption 2014

First do Plotly imports

import plotly.graph_objs as go
from plotly.offline import init_notebook_mode,iplot
init_notebook_mode(connected=True)

Next step is to fetch the dataset, we’ll use Python pandas library to read the read the csv file

import pandas as pd
df = pd.read_csv('2014_World_Power_Consumption')

Next, we need to create data and layout variable which contains a dict

data = dict(type='choropleth',
locations = df['Country'],
locationmode = 'country names', z = df['Power Consumption KWH'],
text = df['Country'], colorbar = {'title':'Power Consumption KWH'},
colorscale = 'Viridis', reversescale = True)

Let’s make a layout

layout = dict(title='2014 World Power Consumption',
geo = dict(showframe=False,projection={'type':'Mercator'}))

Pass the data and layout and plot using iplot

choromap = go.Figure(data = [data],layout = layout)
iplot(choromap,validate=False)

The output will be be like below:

Check github for full code.

In next post I will try to make a choropleth for a different data set.

 References: 

https://www.udemy.com/python-for-data-science-and-machine-learning-bootcamp

      https://plot.ly/python/choropleth-maps/

Web development: LAMP: which programming languages should be used: Some thoughts

Now a days people keep asking which technology stack to be used for web development (LAMP, Java, Microsoft) and finally which programming language mainly server-side. Most of the expert says that use whichever you like and comfortable and I totally agree. If you intend to use Java and Microsoft based env then you don’t have much choice but if you are using LAMP stack then you have a lot of options so question again arises which language should be used? Again, I personally think that decision should mainly on based on the requirement, experience, comfort, team etc. Still here is my take based on my little own experiences working with languages:

Perl:
Pros: Old fellow still widely used, Very powerful, secure, well tested over the years in web dev, very good market repo among users, huge collection of open source libraries, new framework like Dancer, Mojolicious are positive sign.
Cons: Difficult to maintain (dirty syntax etc), Hard to get resources, industry is not very positive about its future versions.

Python:
Pros: Powerful, widely used in handling scientific data, academics, analytics, system administrators, Market sentiment is positive, Very good framework like Django.
Cons: Less flexible, performance issues mainly threading.

PHP:
Pros: Most preferred language, widely used, fast development, big community, huge available resource pool.
Cons: Some reported security loopholes, Less trustworthy, Market image as cheap and dirty option for quick development, multi-threading issue, debugging issues.

Ruby:
Pros: Very flexible, good support, positive image in communities, Very popular framework for web development (ROR).
Cons: Some benchmarks shows that its request-response time is a bit slow than others in same category, Getting good resources can be difficult.

Again few things differ project to project so choose based on your own requirement.

I personally prefer Perl 5.

Switching from Perl to Python: Speed

A real time comparison. Long live Perl.

 

http://silicainsilico.wordpress.com/2012/03/26/switching-from-perl-to-python-speed/

 

Update:

Adding another comparison between various programming languages including Perl. This is bit old post but still relevant.

http://tenser.typepad.com/tenser_said_the_tensor/2006/08/python_vs_perl_.html

 

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