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As such, a DataFrame can be thought of as having two indices: one column-based and one row-based. Because column names are stored as an index, these are not required to be unique. [9]: 103–105 If data is a Series, then data['a'] returns all values with the index value of a. However, if data is a DataFrame, then data['a'] returns all values in ...
See the example tables above and below. See also meta:Help:Sorting#Sort modes and the section about forcing the sort mode of a column. To work data-sort-type=number needs to be in the header cell that contains the sorting icon. In tables with multi-row headers, the sorting icon will be in the lowest header cells.
Timsort has been Python's standard sorting algorithm since version 2.3 (since version 3.11 using the Powersort merge policy [5]), and is used to sort arrays of non-primitive type in Java SE 7, [6] on the Android platform, [7] in GNU Octave, [8] on V8, [9] Swift, [10] and inspired the sorting algorithm used in Rust.
One implementation can be described as arranging the data sequence in a two-dimensional array and then sorting the columns of the array using insertion sort. The worst-case time complexity of Shellsort is an open problem and depends on the gap sequence used, with known complexities ranging from O ( n 2 ) to O ( n 4/3 ) and Θ( n log 2 n ).
Selection sort: Find the smallest (or biggest) element in the array, and put it in the proper place. Swap it with the value in the first position. Repeat until array is sorted. Quick sort: Partition the array into two segments. In the first segment, all elements are less than or equal to the pivot value.
For data in which the maximum key size is significantly smaller than the number of data items, counting sort may be parallelized by splitting the input into subarrays of approximately equal size, processing each subarray in parallel to generate a separate count array for each subarray, and then merging the count arrays.
When data is already organized into a data structure, it may be possible to perform selection in an amount of time that is sublinear in the number of values. As a simple case of this, for data already sorted into an array, selecting the k {\displaystyle k} th element may be performed by a single array lookup, in constant time. [ 27 ]
Block sort begins by performing insertion sort on groups of 16–31 items in the array. Insertion sort is an O(n 2) operation, so this leads to anywhere from O(16 2 × n/16) to O(31 2 × n/31), which is O(n) once the constant factors are omitted. It must also apply an insertion sort on the second internal buffer after each level of merging is ...