Linked Questions
31 questions linked to/from How to efficiently find positions of duplicates?
6
votes
4answers
361 views
1
vote
4answers
243 views
Using Select in Subsets [duplicate]
I have a list:
list = {{7, 6, 14, 14, 4}, {4, 9, 8, 11, 14}, {20, 12, 12, 11, 3}, {7,
4, 11, 7, 20}, {2, 13, 17, 11, 19}}
I did a test to identify where ...
523
votes
19answers
130k views
Where can I find examples of good Mathematica programming practice?
I consider myself a pretty good Mathematica programmer, but I'm always looking out for ways to either improve my way of doing things in Mathematica, or to see if there's something nifty that I haven't ...
69
votes
7answers
5k views
Partitioning with varying partition size
How can I partition a list into partitions whose sizes vary?
The length of the $k$'th partition is a function $f(k)$.
For example: if $l = \{1, 2, 3, 4, 5, 6\}$ and $f(k) = k$. Then
the partitioning ...
21
votes
12answers
4k views
How to get list of duplicates when using DeleteDuplicates?
This might be easy, but can't find a way to use DeleteDuplicates to get also list of the actual duplicates.
Example:
...
10
votes
4answers
5k views
Delete duplicate elements from a list
If a list contains duplicate elements, for example
list = {a, 1, 5, 3, 5, x^2, x^2},
how can the duplicate elements be removed? The result would be
...
21
votes
6answers
3k views
Looking for a way to insert multiple elements into multiple positions simultaneously in a list
I would like to take the following data:
insertValues = {r, x};
insertPositions = {{1}, {5}};
originalList = {a, b, c, d, e, f, g};
and generate output that ...
21
votes
7answers
1k views
How do I obtain an intersection of two or more list of lists conditioned on the first element of each sub-list?
Given two lists like
list1 = {{1, 1}, {2, 4}, {3, 9}, {4, 16}};
list2 = {{2, 6}, {3, 9}, {4, 12}, {5, 15}};
I would like to produce an output like
...
25
votes
5answers
740 views
Partitioning a list when the cumulative sum exceeds 1
I have a long list of say 1 million Uniform(0,1) random numbers, such as:
dat = {0.71, 0.685, 0.16, 0.82, 0.73, 0.44, 0.89, 0.02, 0.47, 0.65}
I want to ...
16
votes
6answers
516 views
Pick elements from list “separately”
I have the following list I want to pick elements from:
mylist = {1, 5, 7, 3, 4, 7, 2, 9, 9, 1, 10, 12, 2, 64, 34, 64}
I have another list with 0's and 1's which ...
46
votes
2answers
1k views
Why is the new PositionIndex horribly slow?
This issue has largely been mitigated in 10.0.1. New timings for the final test below are:
...
11
votes
9answers
459 views
Positions of elements in the initial flattened list in a split list
Say, we have a list:
m1 = {2, 2, 7, 0, 7, 7, 2, 2, 2}
It can be split easily:
...
17
votes
5answers
816 views
Easiest/most efficient way to delete duplicates from one list at the positions of another?
This question is somewhat related to How to efficiently find positions of duplicates? , although I'm interested in something a little bit simpler since I'm not really interested in a list of all the ...
13
votes
5answers
2k views
Match opening and closing parentheses?
Suppose I have a List of the form:
lst={"(", "(", "(", ")", "(", ")", ")", ")"}
By running ...
9
votes
4answers
2k views
Checking for duplicates in sublists
I have a list with contains entries that are length 8 sublists,i.e.
L1={{a1,b1,c1,d1,A1,B1,C1,D1},{a2,b2,c2,d2,A2,B2,C2,D2},...} and so on.
Now, in my problem two ...
