tidyverse pivot_longer several sets of columns, but avoid intermediate mutate_wider steps [duplicate]
来源： https://stackoverflow.com/questions/61361728/tidyverse-pivot-longer-several-sets-of-columns-but-avoid-intermediate-mutate-wi
pivot
How to know total number of active events on any given date based on their start and end dates stored? in Tableau
来源： https://stackoverflow.com/questions/64799461/how-to-know-total-number-of-active-events-on-any-given-date-based-on-their-start
[LeetCode] 81. Search in Rotated Sorted Array II 在旋转有序数组中搜索 II
Follow up for "Search in Rotated Sorted Array": What if duplicates are allowed? Would this affect the run-time complexity? How and why? Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2 ). Write a function to determine if a given target is in the array. The array may contain duplicates. 33. Search in Rotated Sorted Array 的拓展，数组中允许出现重复数字，这个也会影响我们选择哪半边继续搜索，之前判断左右部分是否有序的方法就失效了，因为可能有这种58555情况，虽然起点小于等于中间，但不代表右边就不是有序的，因为中点也小于等于终点，所有右边也是有序的。所以，如果遇到这种中点和两边相同的情况，我们两边都要搜索。 Java： public class Solution { public
按指定基准对齐的分组运算
对照一个基准集合，将待分组集合成员的某个字段或表达式与基准集合成员比较，相同者则分到同一个组中，最后拆分出来的组数和基准集合成员数是相同的。这种分组我们称为对齐分组。对齐分组可能会有空组，也可能有成员未分配到任何一个组中。 1. 普通对齐分组 1.1 每组保留最多一个匹配成员 按某字段的指定顺序，将表中所有记录分组并汇总求和。 【例 1】 根据相互关联的课程表和选课表，按课程表顺序查询有哪些课程无人选择： 【SPL 脚本】 A B 1 =connect("db") /连接数据库 2 =A1.query("select * from SelectCouse") /查询选课表 3 =A1.query("select * from Course") /查询课程表 4 =A2.align(A3:ID,CourseID) /使用函数 A.align()，将选课表按照课程表的 ID 对齐，每组选择一个匹配成员 5 =A3(A4.pos@a(null)) /在课程表中选出没有选择（值为 null）的课程信息 A5 的执行结果如下： ID NAME TeacherID 1 Environmental protection and sustainable development 5 10 Music appreciation 18 1.2 每组保留所有匹配成员 按某字段的指定顺序
How to group by column in a dataframe and create pivot tables in a loop
来源： https://stackoverflow.com/questions/64330740/how-to-group-by-column-in-a-dataframe-and-create-pivot-tables-in-a-loop
How to group by column in a dataframe and create pivot tables in a loop
来源： https://stackoverflow.com/questions/64330740/how-to-group-by-column-in-a-dataframe-and-create-pivot-tables-in-a-loop
How to group by column in a dataframe and create pivot tables in a loop
来源： https://stackoverflow.com/questions/64330740/how-to-group-by-column-in-a-dataframe-and-create-pivot-tables-in-a-loop
How to group by column in a dataframe and create pivot tables in a loop
来源： https://stackoverflow.com/questions/64330740/how-to-group-by-column-in-a-dataframe-and-create-pivot-tables-in-a-loop
Sort with pivot table pandas
来源： https://stackoverflow.com/questions/57670884/sort-with-pivot-table-pandas
SQL SERVER 行列转换(动态)
行转列测试数据： --测试数据 if not object_id(N'Tempdb..#T') is null drop table #T Go Create table #T([Name] nvarchar(22),[Subject] nvarchar(22),[Score] int) Insert #T select N'李四',N'语文',60 union all select N'李四',N'数学',70 union all select N'李四',N'英语',80 union all select N'张三',N'语文',90 union all select N'张三',N'数学',80 union all select N'张三',N'英语',70 Go --测试数据结束 动态写法（加上了总分和平均分）： DECLARE @sql VARCHAR(MAX) SET @sql = 'select Name' SELECT @sql = @sql + ',max(case Subject when ''' + Subject + ''' then Score else 0 end)[' + Subject + ']' FROM ( SELECT DISTINCT Subject FROM #T ) a SET @sql = @sql + ',sum(Score) 总分