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* update presentations * CLICKHOUSE-2936: redirect from clickhouse.yandex.ru and clickhouse.yandex.com * update submodule * lost files * CLICKHOUSE-2981: prefer sphinx docs over original reference * CLICKHOUSE-2981: docs styles more similar to main website + add flags to switch language links * update presentations * Less confusing directory structure (docs -> doc/reference/) * Minify sphinx docs too * Website release script: fail fast + pass docker hash on deploy * Do not underline links in docs * shorter * cleanup docker images * tune nginx config * CLICKHOUSE-3043: get rid of habrastorage links * Lost translation * CLICKHOUSE-2936: temporary client-side redirect * behaves weird in test * put redirect back * CLICKHOUSE-3047: copy docs txts to public too * move to proper file * remove old pages to avoid confusion * Remove reference redirect warning for now * Refresh README.md * Yellow buttons in docs * Use svg flags instead of unicode ones in docs * fix test website instance * Put flags to separate files * wrong flag * Copy Yandex.Metrica introduction from main page to docs * Yet another home page structure change, couple new blocks (CLICKHOUSE-3045) * Update Contacts section * CLICKHOUSE-2849: more detailed legal information * CLICKHOUSE-2978 preparation - split by files * More changes in Contacts block * Tune texts on index page * update presentations * One more benchmark * Add usage sections to index page, adapted from slides * Get the roadmap started, based on slides from last ClickHouse Meetup * CLICKHOUSE-2977: some rendering tuning * Get rid of excessive section in the end of getting started * Make headers linkable * CLICKHOUSE-2981: links to editing reference - https://github.com/yandex/ClickHouse/issues/849 * CLICKHOUSE-2981: fix mobile styles in docs * Ban crawling of duplicating docs * Open some external links in new tab * Ban old docs too * Lots of trivial fixes in english docs * Lots of trivial fixes in russian docs * Remove getting started copies in markdown * Add Yandex.Webmaster * Fix some sphinx warnings * More warnings fixed in english docs * More sphinx warnings fixed * Add code-block:: text * More code-block:: text * These headers look not that well * Better switch between documentation languages * merge use_case.rst into ya_metrika_task.rst * Edit the agg_functions.rst texts * Add lost empty lines * Lost blank lines * Add new logo sizes * update presentations * Next step in migrating to new documentation * Fix all warnings in en reference * Fix all warnings in ru reference * Re-arrange existing reference * Move operation tips to main reference * Fix typos noticed by milovidov@ * Get rid of zookeeper.md * Looks like duplicate of tutorial.html * Fix some mess with html tags in tutorial * No idea why nobody noticed this before, but it was completely not clear whet to get the data * Match code block styling between main and tutorial pages (in favor of the latter) * Get rid of some copypaste in tutorial * Normalize header styles * Move example_datasets to sphinx * Move presentations submodule to website * Move and update README.md * No point in duplicating articles from habrahabr here * Move development-related docs as is for now * doc/reference/ -> docs/ (to match the URL on website) * Adapt links to match the previous commit * Adapt development docs to rst (still lacks translation and strikethrough support) * clean on release * blacklist presentations in gulp * strikethrough support in sphinx * just copy development folder for now * fix weird introduction in style article * Style guide translation (WIP) * Finish style guide translation to English * gulp clean separately * Update year in LICENSE * Initial CONTRIBUTING.md * Fix remaining links to old docs in tutorial * Some tutorial fixes * Typo * Another typo * Update list of authors from yandex-team accoding to git log
74 lines
2.8 KiB
ReStructuredText
74 lines
2.8 KiB
ReStructuredText
Higher-order functions
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----------------------
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-> operator, lambda(params, expr) function
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Allows describing a lambda function for passing to a higher-order function. The left side of the arrow has a formal parameter - any ID, or multiple formal parameters - any IDs in a tuple. The right side of the arrow has an expression that can use these formal parameters, as well as any table columns.
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Examples: ``x -> 2 * x, str -> str != Referer.``
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Higher-order functions can only accept lambda functions as their functional argument.
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A lambda function that accepts multiple arguments can be passed to a higher-order function. In this case, the higher-order function is passed several arrays of identical length that these arguments will correspond to.
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For all functions other than 'arrayMap' and 'arrayFilter', the first argument (the lambda function) can be omitted. In this case, identical mapping is assumed.
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arrayMap(func, arr1, ...)
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~~~~~~~~~~~~~~~~~~~~~~~~~
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Returns an array obtained from the original application of the 'func' function to each element in the 'arr' array.
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arrayFilter(func, arr1, ...)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Returns an array containing only the elements in 'arr1' for which 'func' returns something other than 0.
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Examples:
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.. code-block:: sql
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SELECT arrayFilter(x -> x LIKE '%World%', ['Hello', 'abc World']) AS res
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.. code-block:: text
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┌─res───────────┐
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│ ['abc World'] │
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└───────────────┘
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.. code-block:: sql
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SELECT
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arrayFilter(
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(i, x) -> x LIKE '%World%',
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arrayEnumerate(arr),
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['Hello', 'abc World'] AS arr)
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AS res
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.. code-block:: text
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┌─res─┐
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│ [2] │
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└─────┘
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arrayCount([func,] arr1, ...)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Returns the number of elements in 'arr' for which 'func' returns something other than 0. If 'func' is not specified, it returns the number of non-zero items in the array.
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arrayExists([func,] arr1, ...)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Returns 1 if there is at least one element in 'arr' for which 'func' returns something other than 0. Otherwise, it returns 0.
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arrayAll([func,] arr1, ...)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Returns 1 if 'func' returns something other than 0 for all the elements in 'arr'. Otherwise, it returns 0.
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arraySum([func,] arr1, ...)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Returns the sum of the 'func' values. If the function is omitted, it just returns the sum of the array elements.
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arrayFirst(func, arr1, ...)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Returns the first element in the 'arr1' array for which 'func' returns something other than 0.
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arrayFirstIndex(func, arr1, ...)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Returns the index of the first element in the 'arr1' array for which 'func' returns something other than 0.
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