<< Chapter < Page Chapter >> Page >

Then the subscription selects the value in the mapping that corresponds to that key.

In other words, the system looks up the word in the dictionary and returns the value that corresponds to that word.

I will have more to say about mappings in a future module.

Slicing

I discussed slicing at some length in the earlier module titled Itse1359-1070-Strings Part 2 . I will simply refer you back to that module for the discussion on slicing.

A mutable sequence

According to the Python Language Reference -- 3.2. The standard type hierarchy :

Mutable sequences:

Mutable sequences can be changed after they are created.

There are currently two intrinsic mutable sequence types:

  • Lists - The items of a list are arbitrary Python objects. Lists are formed by placing a comma-separated list of expressions in square brackets. (Note that there are no special cases needed to form lists of length 0 or 1.)
  • Byte Arrays - A bytearray object is a mutable array. They are created by the built-in bytearray() constructor. Aside from being mutable (and hence unhashable), byte arrays otherwise provide the same interface andfunctionality as immutable bytes objects.

This module does not discuss ByteArrays .

A list

According to The Python Tutorial -- 3.1.3. Lists :

"Python knows a number of compound data types, used to group together other values. The most versatile is the list, which can be written as a list of comma-separated values (items) between square brackets. Lists might contain items of different types, but usually the items all have the same type.
Like strings (and all other built-in sequence type), lists can be indexed and sliced.
All slice operations return a new list containing the requested elements."

Some sample programs

Creating, indexing, and slicing lists

A list can be written as a sequence of comma-separated values (items) surrounded by square brackets.

Lists can also be nested within other lists.

List items do not all have to be of the same type.

An example list

The Python script shown in Listing 4 creates a simple list containing four elements of different types. The types of the elements are respectively, a float value, an integer , a string , and another integer .

Listing 4 . An example list.
# Illustrates creating, # indexing, and slicing lists.# #-------------------------------theList = [3.14,59,"A string",1024] print("Print index value 2")print(theList[2])print("Print a short slice") print(theList[0:3]) print("Print the entire list")print(theList[:100])

After creating the list, the program uses a subscription (index) to extract and print the value at index 2 (remember the first item is at index 0) .

Then it uses the slice notation to extract and print two different slices from the list.

The first slice extracts and prints the elements from index 0 through index 2 inclusive. (Remember, the items selected by a slice do not include the index specified by the upper limit value, which is 3 in this case.)

The second slice extracts and prints the entire list. If you don't understand these two slices, go back and review the module titled Itse1359-1070-Strings Part 2 where I discussslicing in detail.

Questions & Answers

what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
How can I make nanorobot?
Lily
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
how can I make nanorobot?
Lily
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!





Source:  OpenStax, Itse 1359 introduction to scripting languages: python. OpenStax CNX. Jan 22, 2016 Download for free at https://legacy.cnx.org/content/col11713/1.32
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Itse 1359 introduction to scripting languages: python' conversation and receive update notifications?

Ask