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Python Data Type Q&A » List » element 

1. What is the time complexity of popping elements from list in Python?    stackoverflow.com

I wonder what is the time complexity of pop method of list objects in Python (in CPython particulary). Also does the value of N for list.pop(N) affects the complexity? ...

2. Python: Alter elements of a list    stackoverflow.com

I have a list of booleans where occasionally I reset them all to false. After first writing the reset as:

for b in bool_list:
    b = False
I found it ...

3. Operation on every pair of element in a list    stackoverflow.com

Using Python, I'd like to compare every possible pair in a list. Suppose I have

my_list = [1,2,3,4]
I'd like to do an operation (let's call it foo) on every combination of 2 elements ...

4. Simple syntax for bringing a list element to the front in python?    stackoverflow.com

I have an array with a set of elements. I'd like to bring a given element to the front but otherwise leave the order unchanged. Do folks have suggestions ...

5. What is the most efficient way to add an element to a list only if isn't there yet?    stackoverflow.com

I have the following code in Python:

def point_to_index(point):
    if point not in points:
        points.append(point)
    return points.index(point)
This code is ...

6. Python most common element in a list    stackoverflow.com

What is an efficient way to find the most common element in a Python list? My list items may not be hashable so can't use a dictionary. Also in case of draws the ...

7. Is there a way to know if a list of elements is on a larger list without using 'in' keyword?    stackoverflow.com

I want to do this. I have two python lists, one larger than the other and I want to know is there is a way to check if the elements of ...

8. Adding Lists Elements to 'Mega List'    stackoverflow.com

Let's say I have a list somewhere called majorPowers which contain these two lists:

axis=["germany","italy","japan"]
allies=["russia","uk","us"]
I'd like to insert each of the elements of these lists, into a new mega-list. I'm currently doing ...

9. How do I determine if an element is in a list?    stackoverflow.com

thelist = [{'color':'green', 'time':4}, {'color':'red','time':2},{'color':'blue','time':5}]
How do I say:
If "red" is in thelist and time does not equal 2 for that element (that's we just got from the list):

10. Python: Elements not in a list    stackoverflow.com

So heres my code:

item = [0,1,2,3,4,5,6,7,8,9]

for item in z:
    if item not in z:
        print item
Z contains a list of integers. ...

11. Getting next element while cycling through a list    stackoverflow.com

li = [0, 1, 2, 3]

running = True
while running:
    for elem in li:
        thiselem = elem
      ...

12. Expanding elements in a list    stackoverflow.com

I'm looking for a "nice" way to process a list where some elements need to be expanded into more elements (only once, no expansion on the results). Standard iterative way would be ...

13. Python - Differences between elements of a list    stackoverflow.com

Given a list of numbers how to find differences between every (i)-th and (i+1)-th of its elements? Should one better use lambda or maybe lists comprehension? Example: Given a list t=[1,3,6,...] it is ...

14. How to get a list with elements that are contained in two other lists?    stackoverflow.com

We have two lists:

a=['1','2','3','4']
b=['2','3','4','5']
How to get a list with elements that are contained in both lists:
a_and_b=['2','3','4']
and a list with elements that are contained only in one list, but not the other:
only_a=['1']
only_b=['5']
Yes, ...

15. How to treat the last element in list differently in Python?    stackoverflow.com

I need to do some special operation for the last element in a list. Is there any better way than this?

array = [1,2,3,4,5] 
for i, val in enumerate(array): 
  if (i+1) ...

16. How to get the nth element of a python list or a default if not available    stackoverflow.com

I'm looking for an equivalent in python of dictionary.get(key, default) for lists. Is there any one liner idiom to get the nth element of a list or a default value if ...

17. Common elements between two lists not using sets in Python    stackoverflow.com

I want count the same elements of two lists. Lists can have duplicate elements, so I can't convert this to sets and use & operator.

a=[2,2,1,1]
b=[1,1,3,3]
set(a) & set(b) work
a & b don't ...

18. In python: how to apply itertools.product to elements of a list of lists    stackoverflow.com

I have a list of arrays and I would like to get the cartesian product of the elements in the arrays. I will use an example to make this more concrete... itertools.product seems ...

19. python: getting element in a list    stackoverflow.com

def do_work():
  medications_subset2(b,['HYDROCODONE','MORPHINE','OXYCODONE'])

def medications_subset2(b,drugs_needed):
  MORPHINE=['ASTRAMORPH','AVINZA','CONTIN','DURAMORPH','INFUMORPH',
            'KADIAN','MS CONTIN','MSER','MSIR','ORAMORPH',
            ...

20. Perform an action over 2 and 2 elements in a list    stackoverflow.com

I have a list of numbers, say

data = [45,34,33,20,16,13,12,3]
I'd like to compute the difference between 2 and 2 items, (that is, for the above data I want to compute 45-34,33-20,16-13 and 12-3, ...

21. Ignore an element while building list in python    stackoverflow.com

I need to build a list from a string in python using the [f(char) for char in string] syntax and I would like to be able to ignore (not insert in ...

22. about python list step issue when the element is long type    stackoverflow.com

In [2]: list=range(627) In [3]: list[::150] Out[3]: [0, 150, 300, 450, 600] the above code is right,but if i use the bellow code,caution:the l means long type, the return result is not like above,what's the ...

23. Why are certain elements of this python list ignored?    stackoverflow.com

I'm new to Python, and i'm struggling to understand the output of this simple program:

list = os.listdir(os.getcwd())
print(list)
print()
for element in list:
    print(element)
    if 'txt' not in ...

24. python list element wise conditional increment    stackoverflow.com

I have been searching this for a while, basically I am trying to conditionally increment a list of element by another list, element-wise... my code is following, but is there a better ...

25. Clone elements of a list    stackoverflow.com

Let's say I have a Python list that looks like this:

list = [ a, b, c, d]
I am looking for the most efficient way performanse wise to get this:
list = [ ...

26. How do I assign incremental names to elements of a list?    stackoverflow.com

How do I assign incremental names in a list?

>>> ccList
['az <az@example.com>', 'cc777 <cc777@example.com>', 'user11 <user11@example.com>']
>>> for i in range(len(ccList)):
    mailTuple = parseaddr(ccList[i])
    cc = mailTuple[0]
 ...

27. How do I access the 1st element of each list in a lists of lists    stackoverflow.com

Example:

numbers = ['1','2','3']
letters = ['a','b','c']
I want to get [1,a] as a results. Yeah I can loop through it, but I'm wondering if there is a fast one line way of doing ...

28. element that appear more that once in the list in Python    stackoverflow.com

Please help (I know that it's a silly question): I have a list d = [' ABA', ' AAB', ' BAA', ' BAA', ' AAB', ' ABA']. How can I exclude elements ...

29. Difference between consecutive elements in list    stackoverflow.com

Possible Duplicate:
Python - Differences between elements of a list
I have a list and I want to find difference between consecutive elements:
a = [0, 4, ...

30. in python, using in, get specific elements    stackoverflow.com

I want to do something like this, but in python : select * from [list] where [element at index n] = 'hello' So far, I have this

    cells = [' ...

31. list of elements    stackoverflow.com

Possible Duplicate:
Iterate over a python sequence in multiples of n?
How to list elements like: ['abcd', 'efghi'] ? Using the next:
test = map(chr, range(97, 123))
for i ...

32. Decompose list of lists into single list with non-iterable list elements    stackoverflow.com

Ref: python decompose a list Flattening a shallow list in Python While the above mentioned solutions are helpful, my problem is slightly different, and I was ...

33. How can I get the only element of a certain type out of a list more cleanly than what I am doing?    stackoverflow.com

I am working with some xml files. The schema for the files specifies that there can only be one of a certain type of element (in this case I am ...

34. How can I create a list containing another list's elements in the middle in python?    stackoverflow.com

I have three lists. Two are returned from functions. The other list, list_c, is being created in the program out of some hardcoded options and some variables, and the contents of ...

35. Add quotes to every list elements    stackoverflow.com

I'm very new to python. I need a simple and clear script to add quotes to every list elements. Let me explain more. Here is the my code.

parameters = ['a', 'b', ...

36. What is a element's reationship to its list    stackoverflow.com

I have a list

myList=[1,2,3,4]
I want to access '1' (i.e the first element of myList). myList is an instance of class/type list & has its own datamembers/attributes [1,2,3,4] so some way I must be ...

37. How do I stop this program from calling a non-existant list element?    stackoverflow.com

import string

## This part of the code initializes the program by recieving inputs and saving
## them as strings.
## It also currently works!

intext = str.lower(raw_input("Please input the text you are going to ...

38. getting elements in a list according to list of indices in python    stackoverflow.com

I have a list of indices, something like:

b=[0,2]  
and a list of elements:
a = ['elem0','elem1','elem2'] 
I need a list that is composed of the elements in ...

39. Increase each list element in all possible ways    stackoverflow.com

I have a list: test = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0] Need to increase each list element in all possible ways using Python standard library. It's a ...

40. How to access a 'window' of elements from a list in every iteration?    stackoverflow.com

Suppose I have a list [a,b,c,d,e], I want to create a list of tuples [(a,b,c),(b,c,d),(c,d,e)]. Is it possible without using array indices as my loop variable? What is the best way ...

41. How do i calculate amount of identic elements in a list?    stackoverflow.com

I Have a (very long) list, with this structure:

li1 = [[1.4, b][1.5, a][1.6, c][1,4, b][1.7,c][1.4, a][1.6,c]]
I want to write a loop that calculate amount of elements li1[i][0]` with identical value, ...

43. Identify elements in the list    python-forum.org

dictionary = {"#":"guy", "nothing":"."} L = stan_pocz() #this is this list above for i in range (len(L)): for j in range (len(L)): if j == guy: ...

44. Gather elements of a list    python-forum.org

45. Separating a list based on element    python-forum.org

>>> x = ['.py', '.pdf'] >>> y = ['1.py', '2.py', 'a.pdf', 'b.pdf'] >>> ext_dict = {k[1:]:[] for k in x} >>> ext_dict {'pdf': [], 'py': []} >>> for f in y: ... parts = f.rsplit('.',1) ... if len(parts) == 1: ... print "%s had no ...

46. Test for the existence of list element    python-forum.org

#! /usr/local/bin/python3 list = ['zero', 'one', 'two', 'three'] list = ['zero', 'one', 'two', 'three', 'four', 'five'] list = ['zero', 'one', 'two', 'three', 'C'] CRecordKey = 4 print ("list ............ ", list) print ("list[1] ......... ", list[1]) print ("list length ..... ", len(list)) if (len(list) > (CRecordKey)) : print("List item exists.") if (list[CRecordKey] == ...

47. srting starts with an element of a list    python-forum.org

Dear All, I have got a list and a string, I want to check if the string starts with any of the elements in the list. I want to avoid map functions etc. I need it as a logival condition so I would like to have it investigated in one line. Is there any solution for this? Thanks

48. What Happens When List Elements Are Changed?    python-forum.org

I have a simple question; even though the method itself may not be efficient, and I would be open to alternate approaches, I think it would be instructive to have this matter clarified for me. Suppose you have a list, say, one with both numbers and strings as elements; or maybe it may work better to have strings with elements of ...

49. calling elements in a list    python-forum.org

50. Changing an element of a list    python-forum.org

I dont really know the index. In the change method user is asked to enter Name and Surname of the one to change. then I have a method to find who that is. It looks like this: Code: Select all def changeSearch(self,fnamn,enamn): tmp = [] ...

51. Accessing elements in list not working    python-forum.org

for frame in range(1260, numberOfFrames+1): d = Interpolate(frame, distList) # returns a list [float, string] print d[1] # if I do this it gives me this error "TypeError: 'float' object is unsubscriptable" print d # this works, it prints ...

52. Double elements in list    python-forum.org

>>> numList = [1,1,2,3,4,4,5,7,7,7,10] >>> for item in set(numList): ... print "Item: %s Duplicates: %s" % (item, numList.count(item)-1) ... Item: 1 Duplicates: 1 Item: 2 Duplicates: 0 Item: 3 Duplicates: 0 Item: 4 Duplicates: 1 Item: 5 Duplicates: 0 Item: 7 Duplicates: 2 Item: 10 Duplicates: 0 >>>

53. Pulling Every Other Element Out of a List    python-forum.org

54. how to detect some element in a list    python-forum.org

55. skipping the first (x) elements in a list?    python-forum.org

Good Morning Guys. I am working on a program that will calculate the shannon diversity index from a user-specified number of ascii files that are created by a LiDAR software application my advisor wrote. I am new to python. The code below brings in the files, puts all the lines in each file into a list, and then parses each of ...

56. A list whose elements are active    python-forum.org

def new_a(first): list_a = [first] for i in off_list: list_a.append(list_a[-1]+i) return list_a off_list = [2,2,2,2] first = 0 list_a = new_a(first) print list_a first = 7 list_a = new_a(first) print list_a # return values: >>> [0, 2, ...

57. List elements that come after    python-forum.org

look, Im not looking for a solution, but since this is the beginners forum I'd expect something like... you're going to need to look into creating lists within dictionaries. I know how to make dictionaries and lists within dictionaries, but I have no idea how to define list elements that come after another. My idea (which doesnt work) goes something like ...

58. for all elements in a list    python-forum.org

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