You can use numpy.argpartition on flattened version of array first to get the indices of top k items, and then you can convert those 1D indices as per the array’s shape using numpy.unravel_index: >>> arr = np.arange(100*100*100).reshape(100, 100, 100) >>> np.random.shuffle(arr) >>> indices = np.argpartition(arr.flatten(), -2)[-2:] >>> np.vstack(np.unravel_index(indices, arr.shape)).T array([[97, 99, 98], [97, 99, 99]]) … Read more
To go the opposite direction which is what I needed: void printxy(int index) { int y = (int)((-1+sqrt(8*index+1))/2); int x = index – y*(y+1)/2; }
You would need something like CREATE UNIQUE INDEX fn_unique_idx ON table1 (CASE WHEN is_deleted=’N’ THEN id ELSE null END, CASE WHEN is_deleted=’N’ THEN name ELSE null END, CASE WHEN is_deleted=’N’ THEN type ELSE null END); An example of the constraint in action SQL> create table table1 ( 2 id number, 3 name varchar2(10), 4 type … Read more
You can determine the maxval with max: maxval = max(my_list) Then get the indices using enumerate and a list comprehension: indices = [index for index, val in enumerate(my_list) if val == maxval] For your example, I get maxval == 58 indices = [5, 10, 11] As per Keyser’s suggestion, you could save iterating over the … Read more
Filtered indexes could be emulated with function indexes and CASE expression(MySQL 8.0.13 and newer): CREATE TABLE t(id INT PRIMARY KEY, myColumn VARCHAR(100)); — NULL are not taken into account with `UNIQUE` indexes CREATE UNIQUE INDEX myIndex ON t((CASE WHEN myColumn <> ‘myText’ THEN myColumn END)); — inserting excluded value twice INSERT INTO t(id, myColumn) VALUES(1, … Read more
What you want to make sure is that the query will use ONLY the index, so make sure that the index covers all the fields you are selecting. Also, since it is a range query involved, You need to have the venid first in the index, since it is queried as a constant. I would … Read more
I don’t believe it will be possible to get O(1) for both insertion and lookup. The minute you add an array (or even fancy, splittable vectors), the insertion becomes O(n). There are ways to mitigate the damage depending on the expected behavior of your list. If there will be a lot more lookups than insertions/deletions, … Read more
The typical way to break up OR predicates is with UNION. Note that your example doesn’t fit well with your indexes. Even if you omitted field1 from the predicate, you’d have field2 >= 1000 OR field3 >= 2000, which can’t use an index. If you had indexes on (field1, field2) and (field1,field3) or field2 or … Read more
Py_ssize_t is signed. See PEP 353, where it says “A new type Py_ssize_t is introduced, which has the same size as the compiler’s size_t type, but is signed. It will be a typedef for ssize_t where available.” You should use Py_ssize_t for indexing. I didn’t find a definitive statement of this in the Cython docs, … Read more
The problem with VARCHAR being used for any KEY is that they can hold WHITE SPACE. White space consists of ANY non-screen-readable character, like spaces tabs, carriage returns etc. Using a VARCHAR as a key can make your life difficult when you start to hunt down why tables aren’t returning records with extra spaces at … Read more