根据另一个数据框替换特定值

Question

首先，让我们从 DataFrame 1 (DF1) 开始:

DF1 <- data.frame(c("06/19/2016", "06/20/2016", "06/21/2016", "06/22/2016", 
                    "06/23/2016", "06/19/2016", "06/20/2016", "06/21/2016",
                    "06/22/2016", "06/23/2016"),
                  c(1, 1, 1, 1, 1, 2, 2, 2, 2, 2),
                  c(149, 150, 151, 152, 155, 84, 83, 80, 81, 97),
                  c(101, 102, 104, 107, 99, 55, 55, 56, 57, 58),
                  c("MTL", "MTL", "MTL", "MTL", "MTL", "NY", "NY", 
                    "NY", "NY", "NY"))
colnames(DF1) <- c("date", "id", "sales", "cost", "city")

我也有 DataFrame 2 (DF2) :

DF2 <- data.frame(c("06/19/2016", "06/27/2016", "06/22/2016", "06/23/2016"),
                  c(1, 1, 2, 2),
                  c(9999, 8888, 777, 555),
                  c("LON", "LON", "QC", "QC"))
colnames(DF2) <- c("date", "id", "sales", "city")

对于 DF1 中的每一行，我必须查看 DF2 中是否有一行具有相同的日期和 ID。如果是，我必须用 DF2 中的值替换 DF1 中的值。

DF2 的列数总是比 DF1 少。如果某列不在 DF2 中，我必须保留该特定列在 DF1 中的原始值。

最终的输出是这样的:

results <- data.frame(c("06/19/2016", "06/20/2016", "06/21/2016", "06/22/2016",
                        "06/23/2016", "06/19/2016", "06/20/2016", "06/21/2016",
                        "06/22/2016", "06/23/2016"),
                      c(1, 1, 1, 1, 1, 2, 2, 2, 2, 2),
                      c(9999, 150, 151, 152, 155, 84, 83, 80, 777, 555),
                      c(101, 102, 104, 107, 99, 55, 55, 56, 57, 58),
                      c("LON", "MTL", "MTL", "MTL", "MTL", "NY", "NY", 
                        "NY", "QC", "QC"))
colnames(results) <- c("date", "id", "sales", "cost", "city")

你有什么建议吗？

Answer 1

您可以使用 data.table 的连接功能。 - 包装:

library(data.table)
setDT(DF1)
setDT(DF2)

DF1[DF2, on = .(date, id), `:=` (city = i.city, sales = i.sales)]

这使:

> DF1
          date id sales cost city
 1: 06/19/2016  1  9999  101  LON
 2: 06/20/2016  1   150  102  MTL
 3: 06/21/2016  1   151  104  MTL
 4: 06/22/2016  1   152  107  MTL
 5: 06/23/2016  1   155   99  MTL
 6: 06/19/2016  2    84   55   NY
 7: 06/20/2016  2    83   55   NY
 8: 06/21/2016  2    80   56   NY
 9: 06/22/2016  2   777   57   QC
10: 06/23/2016  2   555   58   QC

当两个数据集中都有很多列时，使用 mget 更容易而不是键入所有列名。对于问题中使用的数据，它看起来像:

DF1[DF2, on = .(date, id), names(DF2)[3:4] := mget(paste0("i.", names(DF2)[3:4]))]

当你想构造一个需要预先添加的列名向量时，你可以这样做:

cols <- names(DF2)[3:4]
DF1[DF2, on = .(date, id), (cols) := mget(paste0("i.", cols))]