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Concatenation program output

The output from this program is shown in Figure 4 . As you can see, the concatenated list contains the elements of both of the individual lists.

Figure 4 . Concatenation program output.
Create two lists Print listA[3.14, 59, 'A string', 1024] Print listB[2, 4, 6, 16] Concatenate the listsPrint concatenated list [3.14, 59, 'A string', 1024, 2, 4, 6, 16]

Visualize concatenated lists

Create a new list by concatenating two existing lists

The diagram in Figure 5 visualizes the state of the program memory after the three statements in the code box have been executed. This code creates twolist objects and then concatenates them into a third list object pointed to by the variable named listC .

Figure 5. Visualize concatenated lists.

Visualize concatenated lists

As you can see in Figure 5 , the elements in the new list object point to the objects originally pointed to by the elements in the twooriginal list objects. As you can also see, the order of the elements in the two parts of the new list object preserve theorder of the elements in the two original list objects.

Change an element in an original list

The code in Figure 6 was updated with one additional statement that causes element 0 in one of the original list objects to point to a differentobject of type str containing " OK ".

Figure 6. Change an element in an original list.

Change an element in an original list.

However, element 0 in the concatenated list object pointed to by listC continues to point to the object of type float containing 3.14. The important thing to note here is that the pointer in element 0 in the new list object did not follow suite whenthere was a change in one of the elements in one of the original list objects. It still points to the original float object containing 3.14 and it does not point to the new str object containing "OK" . Therefore, even though the new list object was created by concatenating two original list objects, once created, it is not dependent on thefuture contents of the original list objects. Subsequent changes in the contents of the original list objects are not reflected in the contents of the new list object.

Lists are mutable

Unlike strings, the values in a list can be modified after the list is created.

The Python program shown in Listing 6 creates and prints a list. Then it uses a subscription to modify and print the list three times.

Listing 6 . Lists are mutable.
# Illustrates mutating lists ##------------------------------- print("Create and print a list")listA = [3.14,59,"A string",1024] print(listA)print("Modify the list") listA[2]= "New string" print("Print the modified list")print(listA) print("Modify the list again")listA[3] = listA[3]* 2 print("Print the modified list")print(listA) print("Modify the list again")listA[2] = 0.99999print("Print the modified list") print(listA)

Replace a string with another string

The first modification replaces an existing string in the list with a new string.

Multiply an integer element by two

The second modification multiplies an integer value in the list by a factor of two.

Replace a string by a float

The third modification replaces a string in the list by a float value of 0.99999.

List modification program output

The output from the program is shown in Figure 7 .

Figure 7 . List modification program output.
Create and print a list [3.14, 59, 'A string', 1024]Modify the list Print the modified list[3.14, 59, 'New string', 1024] Modify the list againPrint the modified list [3.14, 59, 'New string', 2048]Modify the list again Print the modified list[3.14, 59, 0.99999, 2048]

More to come

There is a lot more for you to learn about lists that is not included in this module. I will continue this discussion of lists, including moresample programs, in a future module.


This section contains a variety of miscellaneous information.

Housekeeping material
  • Module name: Itse1359-1080-Lists Part 1
  • File: Itse1359-1080.htm
  • Published: 10/15/14
  • Revised: 01/31/16

Financial : Although the Connexions site makes it possible for you to download a PDF file for thismodule at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, you should beaware that some of the HTML elements in this module may not translate well into PDF.

I also want you to know that, I receive no financial compensation from the Connexions website even if you purchase the PDF version of the module.

In the past, unknown individuals have copied my modules from cnx.org, converted them to Kindle books, and placed them for sale on Amazon.com showing me as the author. Ineither receive compensation for those sales nor do I know who does receive compensation. If you purchase such a book, please beaware that it is a copy of a module that is freely available on cnx.org and that it was made and published withoutmy prior knowledge.

Affiliation : I am a professor of Computer Information Technology at Austin Community College in Austin, TX.


Questions & Answers

are nano particles real
Missy Reply
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
Lale Reply
no can't
where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
has a lot of application modern world
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
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
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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