小编Joh*_*ohn的帖子

我有两张桌子.

表1包含公司,其位置在名为的列中使用lat/lng坐标进行地理配准the_geom

表2还包含来自Table1的相同公司,而不是地理参考,以及其他数百个地址为地理参考的公司.

我需要做的就是将Table1公司的the_geomlat/lng值插入表2中的相应条目.这些插入可以基于的共同点是列.address

简单的问题,我确定,但我很少使用SQL.

您好我有两个表(表1和表2下文),并希望基于最接近时间戳形成expected_output加入他们的行列.如果可能的话,涉及dplyr的某种解决方案会很好,但如果它进一步使事情变得复杂则不会.

table1 = 
structure(list(date = structure(c(1437051300, 1434773700, 1431457200
), class = c("POSIXct", "POSIXt"), tzone = ""), val1 = c(94L, 
33L, 53L)), .Names = c("date", "val1"), row.names = c(NA, -3L
), class = "data.frame")

table2 = 
structure(list(date = structure(c(1430248288, 1435690482, 1434050843
), class = c("POSIXct", "POSIXt"), tzone = ""), val2 = c(67L, 
90L, 18L)), .Names = c("date", "val2"), row.names = c(NA, -3L
), class = "data.frame")

expected_output = 
structure(list(date = structure(c(1437051300, 1434773700, 1431457200
), class = c("POSIXct", "POSIXt"), tzone = ""), …

我注意到运行这个子查询

SELECT ST_Area(ST_Union(ST_Transform(ST_Intersection((SELECT poly1.the_geom from poly1 WHERE poly1.polygon_type ='P'),poly2.the_geom),3857)))

AS area_of_P FROM poly1,poly2

比运行此连接要慢得多

SELECT ST_AREA(ST_Union(ST_Transform(ST_Intersection(poly1.the_geom,poly2.the_geom),3857)))

AS area_of_poly

来自poly2

在st_intersects上左边连接poly1(poly1.the_geom,poly2.the_geom)

在哪里poly2.polygon_type ='P'

但是,我需要扩展这个第二个连接版本以返回更多列,每个列都计算出给定多边形类型的区域,即

SELECT ST_Area(ST_Union(ST_Transform(ST_Intersection((SELECT poly1.the_geom from poly1 WHERE poly1.polygon_type ='P'),poly2.the_geom),3857)))AS area_of_P,

ST_Area(ST_Union(ST_Transform(ST_Intersection((SELECT poly1.the_geom from poly1 WHERE poly1.polygon_type ='S'),poly2.the_geom),3857)))AS area_of_S

来自poly1,poly2

我正在寻找一种解决方案来添加"desired_result"列,最好使用dplyr和/或ave().请参阅此处的数据框,其中组是"section",我希望我的"desired_results"列按顺序计数的唯一实例位于"exhibit"中:

structure(list(section = c(1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L), exhibit = structure(c(1L, 
2L, 3L, 3L, 1L, 2L, 2L, 3L), .Label = c("a", "b", "c"), class = "factor"), 
desired_result = c(1L, 2L, 3L, 3L, 1L, 2L, 2L, 3L)), .Names = c("section", 
"exhibit", "desired_result"), class = "data.frame", row.names = c(NA, 
-8L))

在下面的数据框中，我想过滤包含人员“a”、“b”和“c”的组：

df <- structure(list(group = c(1, 1, 1, 2, 2, 2, 3, 3, 4, 4, 4, 4), 
person = structure(c(1L, 2L, 1L, 3L, 1L, 2L, 3L, 1L, 1L, 
2L, 3L, 4L), .Label = c("a", "b", "c", "e"), class = "factor")), .Names = 
c("group", 
"person"), row.names = c(NA, -12L), class = "data.frame")