CODEWITHSUNDEEP
python
yong jie
yong jie

Reputation: 73

How to Append a constantly changing value to a list?

I am quite new to the python coding scene and is currently working on a code on Python using a ultrasonic sensor, I want to add the output value into a list (maintaining the list size)where the list is constantly updating with the latest value from the ultrasonic sensor basically OVERWRITTING the list in a sense,

I have seen examples of Append but they are from fix values,

>>> a = [1,2,3]
>>> b = [4,5,6]
>>> a + b
[1, 2, 3, 4, 5, 6]

is there anyway to append with the output from the ultrasonic sensor? Thank you very much

my_list=[100,50,10,20,30,50] #current list

#example of expected output
distance=300
distance=250
distance=230

my_list=[230,250,300,100,50,10]  
# the latest 3 reading will be appended to the front of the list 
# while still maintaining the size of my_list

Do let let me know if further clarification or information is needed, thank you in advance.

Upvotes: 0

Views: 1026

Answers (4)

Manvir
Manvir

Reputation: 779

You can append to the front with the insert function

my_list.insert(0, distance)

and delete last element with

del my_list[-1]

Here I am assuming you are getting sensor data within a loop one at a time.

Upvotes: 1

ppwater
ppwater

Reputation: 2277

you can do this:

distance = 300
distance = 250
distance = 230
my_list = [230, 250, 300, 100, 50, 10]
my_list.append(20)
print(my_list)

this will append 20 to the list and the result is [230, 250, 300, 100, 50, 10, 20]

and if you like to append it to a certain position of your list, then use insert

distance = 300
distance = 250
distance = 230
my_list = [230, 250, 300, 100, 50, 10]
my_list.insert(0, 20) # 0 is the position and 20 is what to append
print(my_list)

at this code, 0 is the position and 20 is what to append. you can change the value

After reading your question carefully this is the code:

my_list=[100,50,10,20,30,50] #current list
threelist = []
for _ in range(4):
    distance=300 # your senser value
    threelist.append(distance)
while len(threelist) > 3: 
    del threelist[0]
my_list = threelist + my_list
while len(my_list) > 6:
    del my_list[-1]
print(my_list)

this code appends distance to threelist then + it to the my_list. and del the last 3 value.
and you can change distance=300 to your senser value. I hope this helped you.

Upvotes: 1

SajanGohil
SajanGohil

Reputation: 969

For every value, you can use my_list.insert(0, new_value) which will insert new value to 1st position. Your code will look something like:

    my_list.insert(0, new_distance) # add new value to beginning (0 index)
    my_list = my_list[:-1] # remove last element to keep the size same

You can also combine those, eg: my_list[:-1].insert(0, new_distance)

Upvotes: 1

Student
Student

Reputation: 23

my_list.append(distance)

.append() is a built in function in lists.

Upvotes: 2

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