Question

我有一个名为df1的数据帧，该数据帧有四列（即id，s，date和value）。值列为空，我想使用名为df2的第二个数据框填充它。 df2充满了id列和许多其他列，这些列均使用其所属的日期来命名。我需要做的是在df1$value中找到df2的相应值，其中日期和ID号都匹配。

示例数据：

set.seed(123)

#df1
df1 <- data.frame(id = 1:100, 
                      s = runif(100,100,1000), 
                      date = sample(seq(as.Date('1999/01/01'), as.Date('2001/01/01'), by="day"), 100), 
                      value = NA)

#df2
df2 <- data.frame(matrix(runif(80000,1,100), ncol=800, nrow=100))[-1]
    names(df2) <- seq(as.Date("1999-01-01"),as.Date("2002-12-31"),1)[c(1:799)]  
    df2 <- cbind(id =  1:100, df2)

Answer 1

一种方法是使用df2将gather转换为长格式，然后执行left_join

library(dplyr)
library(tidyr)

df1 %>%
  left_join(df2 %>% 
             gather(date, value, -id) %>% 
              mutate(date = as.Date(date)), by = c("id", "date"))

#     id   s       date value
#1     1 359 2000-03-15 48.32
#2     2 809 1999-09-01 62.16
#3     3 468 1999-12-23 16.41
#4     4 895 2000-11-26 32.70
#5     5 946 1999-12-18  5.84
#6     6 141 2000-10-09 74.65
#7     7 575 2000-10-25  9.22
#8     8 903 2000-03-17  6.46
#9     9 596 1999-10-25 73.48
#10   10 511 1999-04-17 62.43
#...

数据

set.seed(123)
df1 <- data.frame(id = 1:100, 
              s = runif(100,100,1000), 
 date = sample(seq(as.Date('1999/01/01'), as.Date('2001/01/01'), by="day"), 100))


df2 <- data.frame(matrix(runif(80000,1,100), ncol=800, nrow=100))[-1]
names(df2) <- seq(as.Date("1999-01-01"),as.Date("2002-12-31"),1)[c(1:799)]  
df2 <- cbind(id =  1:100, df2)

Answer 2

您还可以使用melt，然后使用两个键进行左联接：

library(dplyr)
library(reshape2)
set.seed(123)

#df1
df1 <- data.frame(id = 1:100, 
                  s = runif(100,100,1000), 
                  date = sample(seq(as.Date('1999/01/01'), as.Date('2001/01/01'), by="day"), 100), 
                  value = NA)
#df2
df2 <- data.frame(matrix(runif(80000,1,100), ncol=800, nrow=100))[-1]
names(df2) <- seq(as.Date("1999-01-01"),as.Date("2002-12-31"),1)[c(1:799)]  
df2 <- cbind(id =  1:100, df2)

df2<-melt(df2, id.vars = "id", value.name = "Value", variable.name = "date")

df2$date<-as.Date(df2$date, format = "%Y-%m-%d")
df1<-left_join(df1, df2, by = c("id", "date"))

head(df1)
  id        s       date value    Value
1  1 358.8198 2000-03-15    NA 48.31799
2  2 809.4746 1999-09-01    NA 62.15760
3  3 468.0792 1999-12-23    NA 16.41291
4  4 894.7157 2000-11-26    NA 32.70024
5  5 946.4206 1999-12-18    NA  5.83607
6  6 141.0008 2000-10-09    NA 74.64832

Answer 3

我们可以通过data.table连接使用高效的方式。大数据集应该很快

library(data.table)
setDT(df1)[melt(setDT(df2), id.var = 'id')[, 
       date := as.IDate(variable, '%Y-%m-%d')], on = .(id, date)]

通过匹配ID和列名称来检索data.frame的值

3 个答案: