使用Column[B]基于Grouping[A]和Max(计数)[c]选择特定Grouping[A]的内容

Question

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by_g <- (df, A)    
df.new <- by_g %>%
        summarise(v <- max(C))%>% arrange(A)

当列C有最大计数并按A列分组时，我无法获得B列的内容

Answer 1

在按'A‘分组之后，我们可以在slice中使用slice获得与'C’中的max值相对应的行

df %>%
   group_by(A) %>%
   slice(which.max(C)) 

数据

df <- structure(list(A = c("B001", "B001", "B001", "B001", "B002", 
"B002", "B002", "B003", "B003", "B003", "B003", "B003", "B003"
), B = c("", "Elec VoltageAsymmetry", "Pitch LubricationStop", 
"Pitch SafetyTestActiv", "", "Elec VoltageAsymmetry", "Pitch LubricationStop", 
"", "Elec CurrentAsymmetry", "Elec VectorSurgeStop", "Elec VoltageAsymmetry", 
"Pitch FreqConvPitch2 ErrStop", "Pitch LubricationStop"), C = c(1, 
1, 5, 1, 1, 1, 5, 1, 2, 2, 2, 1, 4)), .Names = c("A", "B", "C"
), row.names = c(NA, -13L), class = "data.frame")