Removing multiple ranges of element from a List<Object>

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My list of objects can have such elements eg1:

[vale11, value12, value13, null, null, null, value21, value22, value23, value31, value32, value33]

eg2:

[vale11, value12, value13, null, null, null, null, null, null, value31, value32, value33]

eg3:

[vale11, value12, value13, null, null, null, value21, value22, value23, null, null, null]

eg4:

[vale11, null, value13, null, null, null, value21, value22, value23, value31, value32, null]

I want to remove the null values but not all (note eg4) and only those in a range started from certain index. So in eg1 would be something like:

list.sublist(3, 6).clear();

eg2:

list.sublist(3, 6).clear();
list.sublist(6, 9).clear();//it's not going to work

I know the starting indexes and a number of next elements (always the same)

Sometimes it would be 1 range, sometimes 3 , 5 ... How to clear the original list with the use of a loop or streams ?

You can use your technique with a little twist: order your ranges on the initial index in descending order. The rationale here is that as long as you go from a higher index to a lower index, and the ranges do not "cross over", the indexing is going to remain consistent.

Hence, clearing out sublist(6, 9) followed by sublist(3, 6) is going to work without a problem:

//  0        1       2       3     4     5     6     7     8      9       10       11
[vale11, value12, value13, null, null, null, null, null, null, value31, value32, value33]
//                                           ^^^^^^^^^^^^^^^^ [6, 9)
//                         ^^^^^^^^^^^^^^^^ [3, 6)

How to remove multiple indexes from a list at the same time?, In [9]: remove_indices = [1,2,3] In [10]: somelist = range(10) In [11]: somelist = [i for j, i in approaches, and for me numpy was the winner (if you have elements that fit in numpy): If you can use numpy, then you can delete multiple indices: List<T>.RemoveRange(Int32, Int32) Method is used to remove a range of elements from the List<T>. Properties of List: It is different from the arrays. A list can be resized dynamically but arrays cannot. List class can accept null as a valid value for reference types and it also allows duplicate elements.

Use can do it with a loop:

Below method will remove the elements whose startIndex <= index <= endIndex

<T> List<T> chopList(List<T> originalList, int startIndex, int endIndex) {
    // Your code to check original list, validate startIndex, endIndex must inrange...
    return IntStream.range(0, originalList.size() - 1)
                    .filter(i -> i < startIndex || i > endIndex)
                    .mapToObj(originalList::get)
                    .collect(toList());
}

Python : How to remove multiple elements from list ? – thispointer.com, Suppose we want to remove multiple elements from a list by index range, then we can use del keyword i.e.. Remove multiple elements from list while Iterating Iterate over the list and remove them one by one if its divisible by 3 i.e.

If you want to remove null elements from a List, you can do it as simple as

list.removeIf(Objects::isNull);

Of course, you can restrict the operation to a certain range like

list.subList(start, end).removeIf(Objects::isNull);

If the actual task is to remove predefined ranges from a list (and the information that there might be null elements at these place is actually irrelevant), you can use this answer (process the ranges in descending order), if the ranges don’t overlap.

If the ranges might overlap, you can use

BitSet toRemove = new BitSet(list.size());
toRemove.set(firstRangeStart, firstRangeEnd);
toRemove.set(secondRangeStart, secondRangeEnd);
// etc
for(int e = toRemove.length(), s; e > 0; e = toRemove.previousSetBit(s)+1)
    list.subList((s=toRemove.previousClearBit(e-1))+1, e).clear();

This will fuse adjacent and overlapping ranges before processing the resulting ranges in descending order.

Remove an item from a list in Python (clear, pop, remove, del), In Python, list's methods clear(), pop(), and remove() are used to remove It is also possible to delete items using del statement by specifying a position or range with an Remove multiple items that meet the condition: List comprehensions You can also remove elements from a list with del statements. Is it possible to delete multiple elements from a list at the same time? If I want to delete elements at index 0 and 2, and try something like del somelist[0], followed by del somelist[2], the second statement will actually delete somelist[3]. I suppose I could always delete the higher numbered elements first but I'm hoping there is a better way.

Remove multiple elements from a list in Python, Given a list of numbers, write a Python program to remove multiple elements from a list based on the given condition. Example: Input: [12, 15, 3, 10] Output:  Varun July 2, 2016 How to remove elements from a List based on value or External Criterion 2016-07-02T17:54:50+05:30 C++, std::list, STL No Comment In this article we will discuss how to remove an element from a List by matching a value or by matching some criterion.

4 Ways to Delete From a List in Python - Better Programming, The clear method removes all elements from the list… providing a single index, as well as multiple elements, by providing a range of indices. With numpy arrays you can delete multiple elements like this: import numpy as np a = np.array([1, 2, 5, 6, 7]) ind2remove = [1, 3] print np.delete(a, ind2remove) print a [1 5 7] [1 2 5 6 7] The delete command makes a new object; the original list is unchanged.

Python Remove Multiple elements from list by index range using del , Description:- using python built-in keyword del, we can delete any object. for deleting multiple element from list we can use colon ":" opeartor which form sequence  As you can see based on Figure 2, we just removed the second list element of our example list. In order to delete this list component, we just needed to write a square bracket, a minus sign, and the positioning of the list element we wanted to delete (i.e. [- 2]) behind the name of our list.

Comments
  • Streams are probably not appropriate if you're relying on indexes (which you are in order to know the range).
  • What is the problem? If the problem is that indices shift when elements are deleted, then run through your indices from highest to lowest so only indices that have already been handled shift.
  • Since you are not explaining when a null value ought to be removed and when not, the "examples" are entirely meaningless. We don’t know what should be removed, except for eg1 and eg2, because you are telling us the ranges explicitly. Of course, when you tell us the ranges explicitly, we will also know them without seeing the contents of eg1 and eg2. So why aren’t you using list.sublist(3, 9).clear(); for eg2? And what should be removed from eg3 or eg4? We don’t know.
  • What’s the advantage over the OP’s solution, list.sublist(startIndex, endIndex).clear();?