Question

我有一个数据框，其中包含气候站给定年份中最高和最低的温度-All.Stations数据集：

Station.Name    Year    Month   Day TMAX    TMIN
GRAND MARAIS    1942    7       28    82      60
GRAND MARAIS    1962    3       17    42      22
LEECH LAKE      1956    7       3     72      50
ALBERT LEA 3 SE 1998    1       25    25      15
TWO HARBORS     1933    5       20    77      42
ARGYLE          1922    9       13    NA      NA

我还有一个按气候站分类的完整年份的数据框（即，这些年份是我一年中每天的数据所在的年份）-complete.years数据集：

Station.Name    Year
DULUTH          1904
AGASSIZ REFUGE  1995
LEECH LAKE      1956
GRAND MARAIS    1942
LEECH LAKE      1994

我想仅将第一个数据帧过滤为仅存在“站名”和“年份”并在第二个数据帧中匹配的数据。

正确的结果将是：

Station.Name    Year TMAX
GRAND MARAIS    1942   82
LEECH LAKE      1956   72

这就是我到目前为止使用dplyr所得到的：

Max.Tempurature <- All_Stations %>% 
  group_by(Station.Name, Year) %>%
  select(Station.Name, Year, TMAX) %>%
  filter(min_rank(desc(TMAX)) <= 1) %>%
  filter((Year %in% complete.years$Year & Station.Name %in% complete.years$Station.Name))

我可以按Year和Station.Name进行过滤，但这会在整个数据框中搜索匹配项。

如何按同一观测值中存在的Station.Name和Year进行过滤？

Answer 1

我们可以做一个import pandas as _pd

inner_join

数据

library(dplyr)
inner_join(All.Stations[c(1, 2, 5)], complete.years)
#   Station.Name Year TMAX
#1 GRAND MARAIS 1942   82
#2   LEECH LAKE 1956   72

Answer 2

或与merge

cols <- c('Station.Name', 'Year', 'TMAX')
merge(All.Stations[cols], complete.years, all.x = FALSE)
#  Station.Name Year TMAX
#1 GRAND MARAIS 1942   82
#2   LEECH LAKE 1956   72

数据

All.Stations <- structure(list(Station.Name = c("GRAND MARAIS", "GRAND MARAIS", 
"LEECH LAKE", "ALBERT LEA 3 SE", "TWO HARBORS", "ARGYLE"), Year = c(1942L, 
1962L, 1956L, 1998L, 1933L, 1922L), Month = c(7L, 3L, 7L, 1L, 
5L, 9L), Day = c(28L, 17L, 3L, 25L, 20L, 13L), TMAX = c(82L, 
42L, 72L, 25L, 77L, NA), TMIN = c(60L, 22L, 50L, 15L, 42L, NA
)), .Names = c("Station.Name", "Year", "Month", "Day", "TMAX", 
"TMIN"), class = "data.frame", row.names = c(NA, -6L))

complete.years <- structure(list(Station.Name = c("DULUTH", "AGASSIZ REFUGE", "LEECH LAKE", 
"GRAND MARAIS", "LEECH LAKE"), Year = c(1904L, 1995L, 1956L, 
1942L, 1994L)), .Names = c("Station.Name", "Year"), class = "data.frame", row.names = c(NA, 
-5L))

通过R中的两个条件过滤数据帧

2 个答案:

数据