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Jan
15
comment Average dataset with many repetitions?
@MikeHoneychurch Mean alone triggers this bug. WRI claims it was broken in 10.3.0 and fixed in 10.3.1, but on Windows I still see the wrong result in 10.3.1 when Mean is applied to a list containing a single association (no crash though). Merge@Mean is the workaround.
Jan
15
comment Aggregation queries on lists of associations in 10.3
@ilian I see you marked this issue as fixed in 10.3.1, but I still see the wrong result for Mean[{<|"a" -> 1, "b" -> 2|>}] in that release but not in 10.2 or earlier (using Windows 7 x64).
Jan
13
revised How to get sub property from json result?
fixed a typo
Jan
13
answered How to get sub property from json result?
Jan
12
comment Get the last line from each of a large number of files, transform them, and write all results to a single new file
@alancalvitti I am not aware of any higher-level functionality for such variable-length record extraction in stream-based fashion. Perhaps Leonid's new (as yet unofficial) streaming extensions would be useful when implementing such a thing?
Jan
7
comment Append fixed value to random selection of list
I don't know your full context, but if you are using f := ..., then I'd probably recommend that you use f[] := ... instead. This is a matter to style rather than necessity. I'd be suprised, for example, if {f, f} returned a list with different elements. But getting different elements from {f[], f[]} is unsurprising. Again, this is just a question of convention rather than a language requirement. You might also consider something like f[n_] := RandomChoice[fns][n].
Jan
7
comment Append fixed value to random selection of list
The Cases expression transforms each element of the Hold expression into a function. It is at that point that each list variable gets notionally moved out of the Hold and into a Function. A function definition is also a held context, so the list variable is still not evaluated. It is only when the function is called that the list variable finally appears in a context in which it is evaluated.
Jan
7
revised Append fixed value to random selection of list
added 281 characters in body
Jan
7
answered Append fixed value to random selection of list
Jan
4
comment Using Merge[Identity] and Transpose on a Dataset
Up to v10.3, the data type information is used primarily for formatting the graphical representation of a Dataset or for performing a small number of proactive sanity checks upon a query. I have speculated that future releases may use the type information for data and/or algorithm optimization. I discuss the use of type information more fully in (87479), (89081) and (102696).
Jan
4
awarded  Good Answer
Jan
3
comment How to make CounterIncrement step in increments of 2
@Kuba Yes, the same CounterFunction must be used at all levels (a surprise to me). I have updated my answer to reflect that. Thanks.
Jan
3
revised How to make CounterIncrement step in increments of 2
added explicit treatment for sub- and subsub- items
Jan
3
awarded  Enlightened
Jan
3
awarded  Nice Answer
Dec
28
answered Grouping by total length of elements grouped
Dec
26
answered How to make CounterIncrement step in increments of 2
Dec
25
comment How to use `Shortest` for pattern matching?
duplicate of (72283).
Dec
23
revised A subtlety in Query
elaborated upon why the `anyhead` case gets unwrapped
Dec
23
revised A subtlety in Query
added 12 characters in body