Timeline for How to FoldList over Dataset column without destroying/rebuilding Dataset?
Current License: CC BY-SA 3.0
8 events
| when toggle format | what | by | license | comment | |
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| Jun 8, 2016 at 11:46 | vote | accept | Edmund | ||
| Jun 7, 2016 at 17:15 | comment | added | chuy |
This is probably the same thing in the end (but much wordier!) ds[MapAt[fold,#,{{"R1"},{"R2"}}]&@*Merge[Identity]][Transpose]
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| Jun 7, 2016 at 14:39 | comment | added | WReach |
@Kuba The expression based upon @* does not work due to a limitation in the type inferencer. The result of the first mapping query operator has type Unknown. The second Transpose does not accept an unknown data type. As usual, the operators work just fine if we take the type system out of the picture, e.g. ds // Normal // Query[...]. In the alternate formulation in your response, the type deducer (not inferencer) gets a chance to restore the missing type information enabling the second Transpose to function. Oh, and +1.
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| Jun 7, 2016 at 13:49 | comment | added | J. M.'s missing motivation♦ |
@Edmund, as for your bonus: Prepend[ds, AssociationThread[{"Date", "R1", "R2"} -> {DateObject@{2007, 12, 31}, 100., 100.}]] works fine.
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| Jun 7, 2016 at 13:39 | comment | added | Edmund |
It seems correct syntax. Odd that ds[Query[{"R1" -> fold, "R2" -> fold}]@*Transpose][Transpose] works and it doesn't. Does it have something to do with ascending and descending operators?
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| Jun 7, 2016 at 13:35 | comment | added | Kuba |
@Edmund Do you possibly know why this is not working: ds[Transpose@*Query[{"R1" -> fold, "R2" -> fold}]@*Transpose]?
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| Jun 7, 2016 at 13:32 | comment | added | Edmund |
This is reasonable. The dataset isn't so huge that the double Transpose will be a problem. +1 while we wait for other solutions.
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| Jun 7, 2016 at 13:26 | history | answered | Kuba | CC BY-SA 3.0 |