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Fun with Python

admin — Wed, 01 Sep 2010 03:28:29 +0000

Hey there fellow developers
I have been working with Python lately(specifically Python3) and wanted to share some things I thought were pretty cool from an outsider’s(learning the language) perspective. I hope the following helps with getting to know this great language.. Enjoy


#construct a tuple using()
t=(1,2,3)

#contruct a list using []
 lst= [1,2,4]

#iterate a string and print each character
for i in "This is a String":
	print(i)

#getting the length of a string
print ("length is",len("12345"))	

#test x is in a range
x=6
if(3< x <10 ):
	print( "I am true")
else:
	print( "I am false")

#test membership

if "2" in "1234":
	print("I am in the string")
if int("2") in [1,2,3,4]:
	print( "I am in the list")

#replication
print( "hithreetimes, "*3)

#using math class
import math
print(math.sqrt(4))

#print all methods
print(dir(math))

#named Tuples
import collections
Movie = collections.namedtuple("Movie","title rating")
collection =[Movie("Jaws", 4.0)]
collection.append(Movie("Toy Story", 5.0))
for movie in collection:
	print("I watched {0} and gave it {1} stars".format(movie.title,movie.rating))

#sequence unpacking
head, *rest = [1,2,3,4,5]
print("head is {0} and rest is {1}".format(head,rest))

#passing and unpacking parameters
def fullname(f,m,l):
	print("First Name ="+f)
	print("Middle Name ="+m)
        print("Last Name  ="l)

fakenamelist =["Homer","J","Simpson"]
fullname(*fakenamelist)		

#list comprehensions (print all odd numbers from 0 to 99)
print( [item for item in range(0,100) if item % 2])

#named parameters
def count_animals(number,*,	animal="ducks"):
	return "{0} {1}".format(number,animal)
print( count_animals(3,animal="cows"))
print( count_animals(3))

print(sorted([-1,2,-3],key=abs)) #same order

line = input("enter something.. ")
print("your line was " ,line)

I have been using python for web requests and recommend using the httplib2 library. It has a lot of really nice features.

Mergesort and Quicksort with Dynamic Languages

admin — Sat, 03 Jan 2009 18:10:58 +0000

The other day I was flipping through an algorithms book and came across a section on sorting. I remembered that I had a blast writing them c++ during my undergrad and thought it would be fun to write them in a couple of different languages. I settled on writing a quicksort, and mergesort.
Interesting notes:
1) Python(2.5) returns a None type when appending a value to an empty list which forced me to use ‘+’
>>> ex= [].append()
>>> print ex
>>>None

2) Groovy gave me a java.util.ConcurrentModificationException when I transcribed my Ruby code to Groovy. Because of the fact that I was deleting items from a list that I would read in later(while loop which checks size of left and right), I got this error. Accounting for that, the groovy code is pretty nasty.(anyone that would like to provide a better example without relying on the built in Collections.sort(list) would be welcome)

Here is my code… enjoy!


# javazquez.com
==========MERGE SORT========

-------------RUBY----------------

def merge_sort(ary)
  return ary if (ary.length <= 1)
  half = ary.length/2
  left = merge_sort(ary[0...half])
  right = merge_sort(ary[half..ary.length-1])
  result =[]
#compare first left and first right
  while left.length > 0 and right.length > 0
    result << (left[0] < right[0] ? left.shift : right.shift)
  end
  result.concat((left.length > 0 ? left : right))
  return result
end

ary=[1,5,14,3,2,45,2,0,01,-1]
p merge_sort(ary)


-----------Python Mergesort-------------

def merg_sort(lst):
    if(len(lst) <= 1):  return lst
    left = merg_sort(lst[:len(lst)/2])
    right = merg_sort(lst[len(lst)/2:len(lst)])
    result = []
    while len(left) > 0 and len(right)> 0:
        if( left[0] > right[0]):
            result.append(right.pop(0))
        else:
            result.append(left.pop(0))

    if(len(left)>0): result.extend(merg_sort(left))
    else: result.extend(merg_sort(right))

    return result

print merg_sort([8,7,43,2,5])


--------Erlang Mergesort-------------
-module(mergesort).
-export([ms/1,msTestSuite/1]).

ms(Lst)->break(Lst).
break([]) -> [];
break([L]) -> [L];
break(List) ->
    {Left, Right} = lists:split(length(List) div 2, List),
    merge(break(Left),break(Right)).

merge(L, []) -> L;
merge([], R) -> R;
merge([Lh|Ltail],[Rh|Rtail])->
	 if
	 Lh < Rh -> [Lh | merge(Ltail,[Rh|Rtail])];
	 Lh >= Rh -> [Rh | merge(Rtail,[Lh|Ltail])]
	 end.

%to test, run mergesort:msTestSuite(run).
msTestSuite(run)->
	[mstest1(run),mstest2(run),
	mstest3(run),mstest4(run),
    mstest5(run)].

mstest1(run)-> ms([3,2,1]).
mstest2(run)-> ms([3,3,3,1]).
mstest3(run)-> ms([]).
mstest4(run)-> ms([1]).
mstest5(run)-> ms([123,0,-1,23,2,34,5,678,7,5,8]).


-------------GROOVY MERGESORT--------
def ms(lst){
    if(lst.size() <= 1){return lst}
    def sz=lst.size()
    int half = (int)(sz/2)
    def l = lst [ 0 .. < half]
    def r = lst [ half.. < sz]
    def lft = ms(l)
    def rht  = ms(r)
    def result = []
    def rcnt = 0
    def lcnt = 0
   while( lcnt < lft.size() && rcnt < rht.size()){
        if(lft[lcnt] < rht[rcnt]){
        	result += lft[lcnt++]
		}
        else{
			result += rht[rcnt++]
		}
     }
    if(lcnt < lft.size()){
		result +=  ms(lft[lcnt..< lft.size()])
	}
    else{
		result += ms(rht[rcnt..< rht.size()])
	}
    return result
}

sl=[3,88,5,3,2,1,-2,2]
println ms(sl)



# javazquez.com
========QUICKSORT========

-----RUBY----------------
def quick_sort(ary)
  return ary if(ary.length <= 1)
  greater,less = [],[]
  pos = rand(ary.length)
  pivot = ary[pos]
  ary.delete_at(pos)
  ary.each{|item|
       (item < pivot) ? less << item :greater << item}
  return (quick_sort(less) << pivot).concat(quick_sort(greater))
end

ary=[1,5,14,3,2,45,2,0,01,-1]
p quick_sort(ary)


----------Python Quicksort--------------

import random
def quickSort(lst):
	if(len(lst) <= 1):return lst
	greater = []
	less = []
	pivot = lst.pop(random.randint(0,len(lst)-1))
	for item in lst:
		if(item < pivot): less.append(item)
		else: greater.append(item)
	return quickSort(less)+[pivot]+quickSort(greater)

ary=[1,5,14,3,2,45,2,0,01,-1]


----------Erlang Quicksort--------------
-module(quicksort).
-export([qsort/1]).

qsort([]) ->[];
qsort([Pivot|T]) ->
		lists:append( [qsort([X || X <- T, X < Pivot]),
		[Pivot], qsort([X || X <- T, X >= Pivot]) ).

-------GROOVY QUICKSORT--------------
def quickSort(lst){
	if(lst.size() <= 1){return lst}
	def greater = []
	def less = []
	def pivot = lst.remove(new  Random().nextInt(lst.size()))
	lst.each{item->
		if(item < pivot){ less.add(item)}
		else{greater.add(item)}
	}
	return quickSort(less)+[pivot]+quickSort(greater)
}
print quickSort([1,5,14,3,2,45,2,0,01,-1])

Fun with Python and Gmail API

admin — Wed, 24 Dec 2008 17:58:10 +0000

Yesterday I decided to play with Gmail’s API in order to grab my contacts. To my surprise, it was a snap. Google has instructions for python Here, I wrote my example using Python 2.5 on OS X. Once I had unzipped the GData contents, I just changed to the GData directory and ran
“sudo python setup.py install”
and I was ready to go.

Python Documentation for GDATA

#################################

# javazquez.com

# Google GMAIL API example

##################################

import gdata.contacts.service
user = 'user@gmail.com'

pwd = 'password'

client2 = gdata.contacts.service.ContactsService()

# Authenticate using your Google Docs email address

# and password.

client2.ClientLogin(user, pwd)

contacts_feed = client2.GetContactsFeed()
################################################

# NOTE: The GetContactsFeed does not give back

#		all contacts.

#              This 'problem' can be solved by looping

#		until the contacts_feed.GetNextLink

#             returns  None.

################################################

l=[]

while(contacts_feed) :

	for x in contacts_feed.entry:

		l.append([x.title.text, x.email[0].address])

	ret = contacts_feed.GetNextLink()

 	contacts_feed = client2.GetContactsFeed(ret.href)  if(ret) else ret
print "here are your %d contacts" % len(l)

for contact in l:

	print "%s -> %s" % (contact[0],contact[1])





Output
here are your xxxx contacts

ANDREW  -> adrew@somewhere.com

...

Ruby to Python Primer

admin — Tue, 16 Dec 2008 16:44:15 +0000

If your like me, you bounce around between languages a lot. Lately, I have been writing python code. It’s not Ruby , but it can get the job done. Here is a quick list of similarities between the two languages. I hope it helps… don’t forget to this list in the comments section
#-----find object methods----- s="hello, I am a string"


#ruby

puts s.methods 
#python

print dir(s)
#find out more about a method using python

help(s.split)
#-----view object's class-----

#ruby

s.class 
#python

s.__class__
#------Iterate hashes-------
#ruby

h.each{|key,value| puts "#{key}, #{value}"} 
#python

for key,value in h.iteritems():

  print key, value
#---ternary operators
#ruby

condition ? var = x : var = y
#python.. not exactly an operator, but you get the meaning

#---- var = y  if condition is false

var = x if condition else y     
#----lengths------

#ruby

s="hello, I am a string"

puts "Length of string is #{s.length} or #{s.size}" 
h={:one=>2,:three=>4}

puts "Length of hash is same as string, #{h.length} or #{h.size} "
#python

print("This is the length of a string %s" % len("string"))

print("number of key/value pair= %d" % len({'one':1,'two':2}))
#---slicing lists/arrays

l=[1,2,3,4,5]
#ruby

l[1..3] #=>[2,3]
#python

l[1:3] #=>[2,3]
#--print string multiple times-----
#ruby

4.times{print "hello"} #=> hellohellohellohello
#python

print("hello" * 4) #=> hellohellohellohello

File I/O Part 1

admin — Fri, 27 Jun 2008 22:30:44 +0000

I love to learn and try new languages. Not only is learning a new language fun, many times it teaches me something new about a language that I am already familiar with. The only problem that I have with learning so many languages, is keeping them straight. I decided that I would take a few of the dynamic languages I use most often and compile a list of how to handle File I/O with each of them. If you have a Dynamic language(part 2 of this post will be on static languages) not represented below or have another method of File I/O with the represented languages, please add to the list with its respective File I/O code:D
Without further ado…

//Groovy open file for writing
def target ="filename"
File wf= new File(target)
wf.write( "I am in your file eating your space" )

//Groovy open file for appending
def target ="filename"
File af= new File(target)
af.append("I have all of your base")

//Groovy read each line in file
new File("filename").eachLine{line-> println line}

//Groovy read whole document and put into List

List lines = new File("filename").readLines()
//lines contains two lines that we need
println "first line  $lines[0]"
println "second line $lines[1]"

//Groovy reading one line
File rf= new File("filename") //open for reading
//read first line, trim, assign to tmp
rf.withReader { line ->tmp = line.readLine().trim()}

//Groovy test if file exists
File src = new File(srcFile)
if (src.exists() ){ println "I exist"}
else{println "I don't exist"}

#Ruby openfile for reading
fh = File.new(path, "r")  # open file "path" for reading only
fh.close

#Ruby open file for writing
fout   = File.new(path, "w")  # open file "path" for writing only
fout.puts "Up, Up, Down, Down, Left, Right, Left, Right, B, A, Select, Start"
fout.close

#Ruby open file for apending
fa= File.new("DeleteMe.txt","a")
fa.puts "I am at the end of file"
fa.close

#Ruby read eachline in a file
File.open("file").each { |line| p line}

#Ruby read entire file to string
fh = File.new(filename)
str = fh.read

#Ruby read entire file into array(each line is an element in the array)
fh = File.new(filename)
str = fh.readlines

#Python Write a file
fout = open("DeletMe.txt", "w")
fout.write("Writing to fout\nCheck it out!")
fout.close()

#Python Read an entire file
fin = open("ReadingTest.txt", "r")
fin_text =  fin.read()
fin.close()
print fin_text

#Python read entire file into list
fin = open("ReadingTest.txt", "r")
txt= fin.readlines()
fin.close()
print txt[0]

#Python append to a file
fh= open ( 'DeleteMe.txt', 'a' )
fh.write ( '\n\n\nBottom line.' )
fh.close()

#Perl reading a file
open(FILE,  '<', $file) or die "Can't read $file: $!\n";
while()
{
print ;
}

#Perl append to a file
open(FILE, '>>', $file) or    die "Can't append to $file: $!\n";
print FILE "text";
close(FILE);

#Perl read and write to a file
#+< allows reading and writing, and keeps the data that was
#already in the file.  open() will fail if file doesn't exist.
open(FILE, "+<$file" ) or die ("Can't  read|write: $file\n");
close(FILE);

#Perl read and write to a file
#+>allows writing and reading, but replaces/overwrites the
#data in the file if the file exists. Creates it if it doesn't exist.
open(FILE, "+>$file" ) or die ("Can't write or read:$file \n");

close(FILE);

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