For python users (programming)?

Question

2 questions id like to ask

What is the difference between a tuple and a list?
What is the difference between a list and a dictionary?

Answer 1

A tuple is not modified once created ; if you have a C programming background, then you can think of a tuple as an array of constant ; while a list is modifiable so it can be assigned new elements ot get its elements deleted .

Many functions return tuples as a return value , so that the caller for these functions wouldn't modify the result .



A list is just analogous to an array : It's indexes are numeric ( 0,1,2, ...).

You can think of a dictionary as a list whose indexes can be anything non numerical as long as these indexes are unmodifiable ( strings, tuples, numbers )





BTW, I answered ur other question regarding the countLines(), but seems that Yahoo Answers doesn't retain the indentation , which is essential for Python. So I am sending the same source BUT substitute EACH occurrence of the '@' symbol below with a space so that you get the correct logical indentation for the program to run :P



import sys # for exit()



def countLines() :



@n=0 # to hold the number of lines



@try :

@@f = open ("somefile.txt") // use correct file name and path



@@for line in f :

@@@n = n +1



@@return n



@except :

@@print "File error. The program will end "

@@sys.exit()





numberofLines = countLines()



print 'The file ',numberofLines,'lines'



raw_input()

Answer 2

As far as I know:

You can't modify tuple but you can modify list. This is should be more memory efficient.



List contains just variables that have position in that list (lis[0], lis[-1] ..) but in dictionary you don't have clear position for all variables but you can use other variables as keys ("bookmarks") for your variables. So you create a simple phonebook using:

phonebook = {'Mike':12345, 'Keke':98765, 'Mother': 98123}

now you can fetch Mikes number using phonebook['Mike']

Of course you can use other variables than strings as your keys:

tuple1= ('Dipum', 'Dipam', 'piupou')

tuple2 = ('Pitim', 'Pitam')

dictionary1 = {tuple1:'todii', tuple2:1233, 'magic':tuple1}

dictionary1[tuple1]

dictionary1[dictionary1['magic']]

If you think about it, there is clear reason why you can use tuples as keys but you can't use lists.

Answer 3

by making use of no skill am I an authority in python, yet attempt basically putting forward your variables as numbers i.e. a = 32 b = 31 then attempt it yet back. additionally, if your coding application has a debug mode they you're able to run it from there, or attempt compiling it and sorting out it. What your doing is basically including 32 to the tip of the enter string making it say "Please decide on a extensive style: 32" rather of exclaiming "Please decide on a extensive style:" once you run it the 2d way. This wont provide a or b actual documents , it is going to in basic terms substitute what it says whilst it asks for the extensive style.

Answer 4

go to official site and read docs or wikipedia python section



python.org is official python site