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Results tagged with gathering
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user 81335
Questions on gathering, grouping or clustering data based on certain criteria. This is to be used with primary tags such as list-manipulation, string-manipulation or similar tags, with the primary tag indicating the specific use case.
1
vote
Grouping lists by their first elements and deleting some groups
I added an entry to the data and made it visible with a Red x to test my solution.
Clear["Global`*"];
list = {{1, 4, 1, -3}, {1, 4, 1, -1}, {1, 4, 1, Style[x, Red]}, {1, 4,
2, -2}, {1, 5, 2, -4}, …
- 59.4k
5
votes
Merging and keeping only the sublists whose first two elements are equal
Clear["Global`*"];
list = {{-9, 3, 2}, {-9, 3, 8}, {-9, 4, 3}, {-9, 4, 4}, {-7, 2,
2}, {-7, 2, 10}, {-7, 3, 4}, {-5, 1, 16}, {-5, 2, 4}, {-3, 1,
4}, {-3, 1, 6}, {3, 1, -14}, {3, 2, -8}, {3, …
- 59.4k
6
votes
Accepted
Strange behavior of Gather with DateObject
Compare the outputs of:
Gather[l, #1 === #2 &]
Gather[l, #1 == #2 &]
The default test is SameQ that translates to #1===#2&and this is what you are seeing. Equal does not mean the same. There is a d …
- 59.4k
1
vote
GatherBy[list, f] except with sublists ordered by f's value
SeedRandom[1]
list = RandomSample@Range[10]
manyLists = Table[RandomSample@list, 10]
$$\left(
\begin{array}{cccccccccc}
7 & 2 & 9 & 1 & 8 & 3 & 10 & 4 & 6 & 5 \\
3 & 6 & 9 & 4 & 2 & 5 & 7 & 8 & 10 …
- 59.4k