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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

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
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.
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
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
characteristics of micro business
for teaching engĺish at school how nano technology help us
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
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
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.
what is the actual application of fullerenes nowadays?
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.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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