I have a big data frame df1 that has a column Student which has string values for students name, Grades with numeric values for the grades of an exam. Another data frame df2 that has three columns Class numeric, From To as a range for the grade and Count that summarizes how many students has a specific grade between some value for a specific class.
举个例子：
Stundent <- c("Mark", "Jhon", "Stuart", "Lillie", "Carl", "Jason", "Stewart","Jack")
Grades <- c(7,9,1,6,7,6,4,8)
df1 <- data.frame(Stundent,Grades)
Class <- c(101, 101, 201, 308, 507, 201, 507, 308)
from <- c(1,6,1,1,6,6,1,6)
to <- c(5,10,5,5,10,10,5,10)
Count <- c(0,2,1,0,1,1,1,2)
df2 <- data.frame(Class,from,to,Count)
df2 <- df2[order(df2$Class),]
我期望得到这样的东西
Students <- c("","Mark, Jhon", "Stuart", "Lillie", "","Carl, Jason", "Stewart", "Jack")
df3 <- data.frame(df2, Students)
