在两个数据文件之间使用内部连接，但要获得特定的行数

Question

这是我制作的一段视频，以防文本混淆https://youtu.be/wkVg4dJQHgc

我有两个数据处理程序，名为df1和df2。这两种数据都包含不同类型的教育测试问题，其中度量某些内容，并具有特定的格式。

df1<-structure(list(Measures = c("space and shape", "space and shape", 
    "space and shape", "space and shape", "space and shape", "change and relationships", 
    "change and relationships", "change and relationships", "change and relationships", 
    "change and relationships", "space and shape", "space and shape", 
    "space and shape", "space and shape", "uncertainty and data", 
    "quantity", "uncertainty and data", "uncertainty and data", "uncertainty and data", 
    "quantity", "change and relationships", "change and relationships", 
    "space and shape", "space and shape", "space and shape", "quantity", 
    "quantity", "quantity", "quantity", "quantity", "uncertainty and data", 
    "change and relationships", "quantity", "quantity", "uncertainty and data", 
    "change and relationships", "uncertainty and data", "quantity", 
    "change and relationships", "change and relationships", "quantity", 
    "quantity", "quantity", "quantity", "quantity", "quantity", "change and relationships", 
    "uncertainty and data", "change and relationships", "uncertainty and data", 
    "uncertainty and data", "uncertainty and data", "quantity", "quantity", 
    "quantity", "space and shape", "change and relationships", "quantity", 
    "space and shape", "space and shape", "change and relationships", 
    "change and relationships", "uncertainty and data", "uncertainty and data", 
    "quantity", "change and relationships", "quantity", "change and relationships", 
    "space and shape", "quantity", "quantity", "quantity", "space and shape", 
    "space and shape", "space and shape", "uncertainty and data", 
    "uncertainty and data", "uncertainty and data", "change and relationships", 
    "change and relationships", "change and relationships", "uncertainty and data", 
    "uncertainty and data", "uncertainty and data", "change and relationships", 
    "change and relationships", "change and relationships", "change and relationships", 
    "change and relationships", "uncertainty and data", "space and shape", 
    "space and shape", "uncertainty and data", "uncertainty and data", 
    "uncertainty and data", "uncertainty and data", "uncertainty and data", 
    "quantity", "quantity", "space and shape", "space and shape", 
    "space and shape", "space and shape", "change and relationships", 
    "space and shape", "space and shape", "quantity", "change and relationships", 
    "change and relationships"), Format = c("Constructed Response Expert", 
    "Constructed Response Manual", "Constructed Response Expert", 
    "Simple Multiple Choice", "Constructed Response Auto-coded", 
    "Constructed Response Expert", "Constructed Response Expert", 
    "Constructed Response Expert", "Complex Multiple Choice", "Complex Multiple Choice", 
    "Complex Multiple Choice", "Simple Multiple Choice", "Constructed Response Expert", 
    "Constructed Response Expert", "Complex Multiple Choice", "Constructed Response Manual", 
    "Simple Multiple Choice", "Complex Multiple Choice", "Simple Multiple Choice", 
    "Constructed Response Manual", "Constructed Response Manual", 
    "Constructed Response Expert", "Simple Multiple Choice", "Constructed Response Expert", 
    "Constructed Response Auto-coded", "Constructed Response Manual", 
    "Complex Multiple Choice", "Constructed Response Manual", "Simple Multiple Choice", 
    "Simple Multiple Choice", "Simple Multiple Choice", "Simple Multiple Choice", 
    "Complex Multiple Choice", "Simple Multiple Choice", "Constructed Response Auto-coded", 
    "Constructed Response Expert", "Constructed Response Manual", 
    "Constructed Response Manual", "Constructed Response Expert", 
    "Constructed Response Manual", "Complex Multiple Choice", "Constructed Response Expert", 
    "Simple Multiple Choice", "Constructed Response Expert", "Constructed Response Manual", 
    "Simple Multiple Choice", "Constructed Response Expert", "Simple Multiple Choice", 
    "Constructed Response Manual", "Simple Multiple Choice", "Simple Multiple Choice", 
    "Simple Multiple Choice", "Constructed Response Manual", "Constructed Response Manual", 
    "Simple Multiple Choice", "Simple Multiple Choice", "Constructed Response Expert", 
    "Constructed Response Manual", "Constructed Response Manual", 
    "Simple Multiple Choice", "Constructed Response Manual", "Constructed Response Expert", 
    "Simple Multiple Choice", "Simple Multiple Choice", "Simple Multiple Choice", 
    "Constructed Response Expert", "Constructed Response Manual", 
    "Simple Multiple Choice", "Constructed Response Expert", "Simple Multiple Choice", 
    "Constructed Response Manual", "Constructed Response Expert", 
    "Complex Multiple Choice", "Complex Multiple Choice", "Constructed Response Expert", 
    "Constructed Response Expert", "Constructed Response Manual", 
    "Constructed Response Expert", "Constructed Response Manual", 
    "Constructed Response Expert", "Constructed Response Expert", 
    "Constructed Response Manual", "Constructed Response Expert", 
    "Constructed Response Expert", "Simple Multiple Choice", "Simple Multiple Choice", 
    "Constructed Response Manual", "Constructed Response Expert", 
    "Simple Multiple Choice", "Constructed Response Expert", "Constructed Response Manual", 
    "Complex Multiple Choice", "Constructed Response Manual", "Constructed Response Manual", 
    "Complex Multiple Choice", "Simple Multiple Choice", "Simple Multiple Choice", 
    "Simple Multiple Choice", "Constructed Response Manual", "Simple Multiple Choice", 
    "Constructed Response Expert", "Constructed Response Manual", 
    "Constructed Response Manual", "Constructed Response Expert", 
    "Constructed Response Manual", "Constructed Response Expert", 
    "Simple Multiple Choice", "Constructed Response Manual", "Complex Multiple Choice"
    )), row.names = c(NA, -109L), class = "data.frame")
    






   df2<- structure(list(Measures = c("space and shape", "space and shape", 
"space and shape", "space and shape"), Format = c("Constructed Response Expert", 
"Constructed Response Manual", "Simple Multiple Choice", "Constructed Response Auto-coded"
)), row.names = c(1L, 2L, 4L, 5L), class = "data.frame")

我使用这段代码来子集第一个dataframe的所有行，这些行都在第二个dataframe中。

library(tidyverse)
inner_join(df1, df2)

但是，假设我的df2实际上是这样的，它的末尾有一个额外的列，它告诉我我希望从df1中得到多少这样的行。例如，在下面的图片中，它说我想要2问题，它测量空间和形状，格式是构造的响应格式

 df2<- structure(list(Measures = c("space and shape", "space and shape", 
    "space and shape", "space and shape", "asdaf"), Format = c("Constructed Response Expert", 
    "Constructed Response Manual", "Simple Multiple Choice", "Constructed Response Auto-coded", 
    "asfas"), Number = c(2, 1, 2, 1, 0)), row.names = c("1", "2", 
    "4", "5", "6"), class = "data.frame")

在此之前，我收到了9种这样的问题。但我想问两个这样的问题。

Answer 1

一种可能的解决办法：

library(tidyverse)

inner_join(df1,df2) %>% 
  group_by(Measures, Format) %>% 
  slice(n=1:min(Number)) %>% 
  ungroup

#> Joining, by = c("Measures", "Format")
#> # A tibble: 6 × 3
#>   Measures        Format                          Number
#>   <chr>           <chr>                            <dbl>
#> 1 space and shape Constructed Response Auto-coded      1
#> 2 space and shape Constructed Response Expert          2
#> 3 space and shape Constructed Response Expert          2
#> 4 space and shape Constructed Response Manual          1
#> 5 space and shape Simple Multiple Choice               2
#> 6 space and shape Simple Multiple Choice               2