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Program output

The output from this program is shown in Figure 1 .

Figure 1 . Program output.
Print index value 2 A stringPrint a short slice [3.14, 59, 'A string']Print the entire list [3.14, 59, 'A string', 1024]

Visualize sliced lists

Create new lists by slicing an existing list

Figure 2 shows the output from the code visualizer for code similar to the code in Listing 4 . Instead of accessing the list elements and printing them on the fly as in Listing 4 , the code in Figure 2 accesses the list elements and saves references to them so that we can see what the resulting lists look like.

Figure 2. Visualize sliced lists.

Visualize sliced lists.

The diagram on the right in Figure 2 shows the state of the program in memory following the execution of all the code in the code box on the left. Asyou can see, there are now three separate lists:

  • the original list pointed to by the variable named theList and
  • two new lists pointed to by bList and cList .

The two new lists were created by slicing the original list. The elements in the lists allpoint to the float , int , and str objects that were used to populate the original list.

Figure 2 illustrates a very important concept. Three of the variables shown in the light blue box point to objects of type list. Theelements that populate those list objects point to other objects of the types float , int , and str (This concept is often called indirection.)

Since the two bottom lists were created as slices of the original (top) list, they all point to the same objects at this stage in the execution of theprogram.

Change an item in the original list

Figure 3 shows what happens when one of the elements of the original list object is modified to cause it to point to a different object. (Note the arrow that now points from element 2 in the original list object down the screen to a new str object containing the word "changed" .)

Figure 3. Change an item in the original list.

Change an item in the original list.

The important thing to note here is that the pointers in element 2 in the other twolist objects did not follow suite. In other words, they still point to the original str object containing the words "A string" and they do not point to the new str object containing the word "changed" . Thus, even though the two new list objects werecreated as slices from the original list object, once they are created, they are not dependent on thecontents of the original list object. Subsequent changes in the contents of the original list object are not reflected in the contents of the two newlist objects.

Lists can be concatenated

Lists can be concatenated using the + operator.

A concatenation program

The Python program shown in Listing 5 creates two lists and prints them both. Then it concatenates the two lists and prints the concatenated version.

Listing 5 . Lists can be concatenated.
# Illustrates concatenating lists ##------------------------------- print("Create two lists")listA = [3.14,59,"A string",1024] listB = [2,4,6,16]print("Print listA") print(listA)print("Print listB") print(listB)print("Concatenate the lists") listC = listA + listBprint("Print concatenated list") print(listC)

Questions & Answers

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
Do somebody tell me a best nano engineering book for beginners?
s. Reply
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?
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
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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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
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