[personal kdb+] Help: explanation kdb-tick

[TerryLynch]

That's a pretty recent change, the commit is detailed here by Charlie: https://github.com/KxSystems/kdb-tick/commit/afc67eda6dfbb2ca89322f702db23ee68c2c7be3#diff-2a42c560e...

Originally .u.add would return the empty schema (0#v) but in order to preserve grouped attribute on sym column it now uses index/apply to ensure the attribute is maintained

Terry

[dotsch]

This is functional amend.

https://code.kx.com/v2/ref/amend/#functional-amend

@[t;`sym;`g#] will apply the `g attribute on t's sym column. t can be a table (or dict) or the name of the table (or dict) as a sym or even file path sym to a (eg. splayed table) folder. For sym t the data is modified inplace and t is returned, otherwise the modified data is returned.

In this particular case this will return the table schema with sym having the `g attribute.

Regards,

András

Guillaume Robin <robinguillaume.pro@gmail.com> ezt írta (időpont: 2019. nov. 26., K 10:59):

Hi,

I'm currently deep diving in the code of kdb-tick and I have difficulties to understand one specific part of the code. Actually, is the last part I need to understand to clearly read kdb-tick.

Here is the code :

add:{

  $[

    (count w x)>i:w[x;;0]?.z.w;

    .[`.u.w;(x;i;1);union;y];

    w[x],:enlist(.z.w;y)

  ];

  (x;

    $[99=type v:value x;

      sel[v]y;

      @[0#v;`sym;`g#] / here is my problem

    ]

  ) 

}

It will be very kind if anyone can give me a detailed explanation. Otherwise, resources will be fine.

I already understood it was about @ verb but I don

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[robinguillaume_]

Thank you a lot for your time!

I will dive into it

Le mardi 26 novembre 2019 11:13:48 UTC+1, TerryLynch a écrit :

That's a pretty recent change, the commit is detailed here by Charlie: https://github.com/KxSystems/kdb-tick/commit/afc67eda6dfbb2ca89322f702db23ee68c2c7be3#diff-2a42c560e...

Originally .u.add would return the empty schema (0#v) but in order to preserve grouped attribute on sym column it now uses index/apply to ensure the attribute is maintained

Terry

[robinguillaume_]

Thank you a lot!

It is very well explained.

Kind regards,

Guillaume

Le mardi 26 novembre 2019 12:36:19 UTC+1, András Dőtsch a écrit :

This is functional amend.

https://code.kx.com/v2/ref/amend/#functional-amend

@[t;`sym;`g#] will apply the `g attribute on t's sym column. t can be a table (or dict) or the name of the table (or dict) as a sym or even file path sym to a (eg. splayed table) folder. For sym t the data is modified inplace and t is returned, otherwise the modified data is returned.

In this particular case this will return the table schema with sym having the `g attribute.

Regards,

András

Guillaume Robin <robingui...@gmail.com> ezt írta (időpont: 2019. nov. 26., K 10:59):

Hi,

I'm currently deep diving in the code of kdb-tick and I have difficulties to understand one specific part of the code. Actually, is the last part I need to understand to clearly read kdb-tick.

Here is the code :

add:{

  $[

    (count w x)>i:w[x;;0]?.z.w;

    .[`.u.w;(x;i;1);union;y];

    w[x],:enlist(.z.w;y)

  ];

  (x;

    $[99=type v:value x;

      sel[v]y;

      @[0#v;`sym;`g#] / here is my problem

    ]

  ) 

}

It will be very kind if anyone can give me a detailed explanation. Otherwise, resources will be fine.

I already understood it was about @ verb but I don

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