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using tidyr unnest with NULL values

由 允我心安 提交于 2019-11-29 20:21:03
问题 I converted a JSON file into a data.frame with a a nested list structure, which I would like to unnest and flatten. Some of the values in the list are NULL, which unnest does not accept. If I replace the NULL values with a data.frame structure that has only NA values, I get the desired result. Below is a simplified example of my problem. I have tried to replace the NULL values with the NA data.frame but did not manage because of the the nested structure. How can I achieve the desired result?

PostgreSQL - text Array contains value similar to

由 六月ゝ 毕业季﹏ 提交于 2019-11-28 12:38:37
I'm trying to get rows where a column of type text[] contains a value similar to some user input. What I've thought and done so far is to use the 'ANY' and 'LIKE ' operator like this: select * from someTable where '%someInput%' LIKE ANY(someColum); But it doesn't work. The query returns the same values as that this query: select * from someTable where 'someInput' = ANY(someColum); I've got good a result using the unnest() function in a subquery but I need to query this in WHERE clause if possible. WHY doesn't the LIKE operator work with the ANY operator and I don't get any errors? I thought

Parallel unnest() and sort order in PostgreSQL

由 本秂侑毒 提交于 2019-11-27 09:18:33
I understand that using SELECT unnest(ARRAY[5,3,9]) as id without an ORDER BY clause, the order of the result set is not guaranteed. I could for example get: id -- 3 5 9 But what about the following request: SELECT unnest(ARRAY[5,3,9]) as id, unnest(ARRAY(select generate_series(1, array_length(ARRAY[5,3,9], 1)))) as idx ORDER BY idx ASC Is it guaranteed that the 2 unnest() calls (which have the same length) will unroll in parallel and that the index idx will indeed match the position of the item in the array? I am using PostgreSQL 9.3.3. Erwin Brandstetter Yes, that is a feature of Postgres

Find rows where text array contains value similar to input

由 。_饼干妹妹 提交于 2019-11-27 06:58:41
问题 I'm trying to get rows where a column of type text[] contains a value similar to some user input. What I've thought and done so far is to use the 'ANY' and 'LIKE ' operator like this: select * from someTable where '%someInput%' LIKE ANY(someColum); But it doesn't work. The query returns the same values as that this query: select * from someTable where 'someInput' = ANY(someColum); I've got good a result using the unnest() function in a subquery but I need to query this in WHERE clause if

Parallel unnest() and sort order in PostgreSQL

由 空扰寡人 提交于 2019-11-26 17:49:24
问题 I understand that using SELECT unnest(ARRAY[5,3,9]) as id without an ORDER BY clause, the order of the result set is not guaranteed. I could for example get: id -- 3 5 9 But what about the following request: SELECT unnest(ARRAY[5,3,9]) as id, unnest(ARRAY(select generate_series(1, array_length(ARRAY[5,3,9], 1)))) as idx ORDER BY idx ASC Is it guaranteed that the 2 unnest() calls (which have the same length) will unroll in parallel and that the index idx will indeed match the position of the

Split given string and prepare case statement

由 旧城冷巷雨未停 提交于 2019-11-26 06:08:44
问题 Table : table_name create table table_name ( given_dates timestamp, set_name varchar ); Insertion of records : insert into table_name values(\'2001-01-01\'),(\'2001-01-05\'),(\'2001-01-10\'), (\'2001-01-15\'),(\'2001-01-20\'),(\'2001-01-25\'), (\'2001-02-01\'),(\'2001-02-05\'),(\'2001-02-10\'), (\'2001-02-15\'); Now I want to update set_name for some dates. For example : I want to update table like this: given_dates set_name ---------------------- 2001-01-01 s1 2001-01-05 s1 2001-01-10 s2
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