library(dplyr)
a <- data_frame(id = c("A","A","A","B","B","B"),
b = c(1.2, 1.5, 1.8, 1.1, 1.6, 1.4))
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现在,我想为id中的每个catergories检索最接近1.43的值.我以为我可以用:
a %>% group_by(id) %>% nth(which.min(abs(.$b-1.43)))
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但是dplyr说
Error: Don't know how to generate default for object of class grouped_df/tbl_df/tbl/data.frame
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