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我想传递一个自定义的一个R函数里面spark_apply但继续运行到问题,并不能找出一些错误的意思。sparklyr spark_apply用户定义函数的错误
library(sparklyr)
sc <- spark_connect(master = "local")
perf_df <- data.frame(predicted = c(5, 7, 20),
actual = c(4, 6, 40))
perf_tbl <- sdf_copy_to(sc = sc,
x = perf_df,
name = "perf_table")
#custom function
ndcg <- function(predicted_rank, actual_rank) {
# x is a vector of relevance scores
DCG <- function(y) y[1] + sum(y[-1]/log(2:length(y), base = 2))
DCG(predicted_rank)/DCG(actual_rank)
}
#works in R using R data frame
ndcg(perf_df$predicted, perf_df$actual)
#does not work
perf_tbl %>%
spark_apply(function(e) ndcg(e$predicted, e$actual),
names = "ndcg")