library(data.table)
library(dplyr)
case1
a1 <- data.table(
a = c("a", "b", "c", "d"),
b = c(1:12)
)
b1 <- data.table(
a = c("a", "b", "e", "d")
)
a1[b1, on = "a"]
case2
a1 <- data.table(
a = c("中文1", "中文2", "中文3", "中文4"),
b = c(1:12)
)
b1 <- data.table(
a = c("中文1", "中文2", "中文5", "中文4")
)
a1[b1, on = "a"]
case3
a1 <- data.table(
a = c("中文一", "中文二", "中文三", "中文四"),
b = c(1:12)
)
b1 <- data.table(
a = c("中文一", "中文二", "中文五", "中文四")
)
a1[b1, on = "a"]
something wrong !!!!!!!!!!!!!!
a1[a == "中文一"]
something wrong !!!!!!!!!!!!!!
b1 %>%
left_join(
a1,
by = "a"
)
case4
a1 <- data.table(
a = c("中文一", "中文二", "中文三", "中文四"),
b = c(1:12)
)
b1 <- data.table(
a = c("中文一", "中文二", "中文三", "中文五")
)
a1[b1, on = "a"]
library(data.table)
library(dplyr)
case1
a1 <- data.table(
a = c("a", "b", "c", "d"),
b = c(1:12)
)
b1 <- data.table(
a = c("a", "b", "e", "d")
)
a1[b1, on = "a"]
case2
a1 <- data.table(
a = c("中文1", "中文2", "中文3", "中文4"),
b = c(1:12)
)
b1 <- data.table(
a = c("中文1", "中文2", "中文5", "中文4")
)
a1[b1, on = "a"]
case3
a1 <- data.table(
a = c("中文一", "中文二", "中文三", "中文四"),
b = c(1:12)
)
b1 <- data.table(
a = c("中文一", "中文二", "中文五", "中文四")
)
a1[b1, on = "a"]
something wrong !!!!!!!!!!!!!!
a1[a == "中文一"]
something wrong !!!!!!!!!!!!!!
b1 %>%
left_join(
a1,
by = "a"
)
case4
a1 <- data.table(
a = c("中文一", "中文二", "中文三", "中文四"),
b = c(1:12)
)
b1 <- data.table(
a = c("中文一", "中文二", "中文三", "中文五")
)
a1[b1, on = "a"]