将 R 中两个不同 table 的值相乘

Question

我有两个从矩阵转换而来的表格：

Table 1:
Column1     Column2    Value
1          A          3
1          B          4
1          C          5
2          A          1
2          B          2
2          C          3

Table 2
Column1     Column2    Value
1          C         5
2          C          1
2          B          2

如果这两个表具有相同的标准，我想将它们的值相乘。例如：

If [Table1[Column1] == Table2[Column1] AND Table1[Column2]==Table2[Column2]
THEN Table1[Value] <- Table1[Value]*Table2[Value]

预期输出：

Table 1:
Column1     Column2    Value
1          A          3
1          B          4
1          C          5*5 - from table 2
2          A          1
2          B          2*2 from table 2
2          C          3*1 - from table 2

我试了几天创建脚本，但遇到了很多问题。

Answer 1

我们可以做一个连接然后做乘法

library(data.table)
setDT(Table1)[Table2, Value := Value * i.Value, on = .(Column1, Column2)]
Table1
#   Column1 Column2 Value
#1:       1       A     3
#2:       1       B     4
#3:       1       C    25
#4:       2       A     1
#5:       2       B     4
#6:       2       C     3

注意：该解决方案就地赋值，速度非常快

数据

Table1 <- structure(list(Column1 = c(1L, 1L, 1L, 2L, 2L, 2L), Column2 = c("A", 
"B", "C", "A", "B", "C"), Value = c(3L, 4L, 5L, 1L, 2L, 3L)), .Names = c("Column1", 
"Column2", "Value"), class = "data.frame", row.names = c(NA, 
 -6L))

Table2 <- structure(list(Column1 = c(1L, 2L, 2L), Column2 = c("C", "C", 
"B"), Value = c(5L, 1L, 2L)), .Names = c("Column1", "Column2", 
 "Value"), class = "data.frame", row.names = c(NA, -3L))

Answer 2

先合并，再相乘

names(table2)[3] <- 'Value2'

table3 <- merge(table1, table2, all.x = TRUE)
table3$Value <- with(table3, ifelse(is.na(Value2), Value, Value * Value2))

将 R 中两个不同 table 的值相乘

Multiply value from two different table in R

r

matrix

counting

数据