我试着从这里Mean by factor by level代码,但它不工作。这是我的情况。从航班数据集中,我想知道UA航空公司所有飞机的平均航班延误。 library(nycflights13)mean(flights$air_time[flights$carrier == "UA"]) 但是结果就是 [1] NA 我做错什么了?
使用的绘图函数是PerformanceAnalytics.包中的charts.PerformanceSummary。charts.PerformanceSummary(RETURNS, na.rm#RETURNS has an NA value and RETSBYDAY has none; including na.rm=T makes