R中的中位数需要数字数据

Question

我试图计算给定向量的中位数,但是当我尝试时我不断收到错误:

median(returns)
Error in median.default(returns) : need numeric data

> returns
 [1] 0.001262733  -0.005048584 -0.009160197 0.010411955  -0.00542421 
 [6] -0.010982649 -0.005807832 0.000863131  -0.00210823  0.000117543 
[11] 0.001319904  0.005307534  0.005246006  0.008469327  0.006006664 
[16] -0.001411188 -0.011446652 0.002669714  0.003896259  -0.003060607
[21] 0.006306116  0.000895311  -0.006235211 -0.000856819 -0.00056599 
[26] 0.00808345   0.00038652   -0.004070623 0.008398158  -0.005976036
[31] 0.011270873  0.007959499  0.003776885  -0.000591663 0.001163452 
[36] 0.005759682  0.000678132  0.000609123  -0.000735042
40 Levels: -0.00056599 -0.000591663 -0.000735042 -0.000856819 ... 0.011270873

dput(returns)
structure(c(25L, 9L, 14L, 39L, 10L, 15L, 11L, 22L, 6L, 18L, 26L, 
31L, 30L, 38L, 33L, 5L, 16L, 27L, 29L, 7L, 34L, 23L, 13L, 4L, 
1L, 36L, 19L, 8L, 37L, 12L, 40L, 35L, 28L, 2L, 24L, 32L, 21L, 
20L, 3L), .Label = c("-0.00056599", "-0.000591663", "-0.000735042", 
"-0.000856819", "-0.001411188", "-0.00210823", "-0.003060607", 
"-0.004070623", "-0.005048584", "-0.00542421", "-0.005807832", 
"-0.005976036", "-0.006235211", "-0.009160197", "-0.010982649", 
"-0.011446652", "#DIV/0!", "0.000117543", "0.00038652", "0.000609123", 
"0.000678132", "0.000863131", "0.000895311", "0.001163452", "0.001262733", 
"0.001319904", "0.002669714", "0.003776885", "0.003896259", "0.005246006", 
"0.005307534", "0.005759682", "0.006006664", "0.006306116", "0.007959499", 
"0.00808345", "0.008398158", "0.008469327", "0.010411955", "0.011270873"
), class = "factor")

Answer 1

由于您是从excel中读取它,因此R正在查看"DIV#0"消息并将您的数据视为分类,就好像它是"蓝色","绿色","淡褐色"等数据一样.所以当你问的是median,R正在考虑你要求的眼睛颜色的中位数,这是没有意义的.

要将一系列因子转换为数字:

returns.numbers <- as.numeric(as.vector(returns))
median(returns.numbers)