在这种情况下，tapply（参数长度不等）有什么问题？

Question

数据取自那里http://open.canada.ca/data/en/dataset/b52664cf-bfd9-49ad-849a-cb88c92553b9（英文版）

 glacier <- read.csv("glacier.csv", stringsAsFactors = F)
 str(glacier)
'data.frame':   518 obs. of  6 variables:
 $ Ref_Date  : int  1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 ...
 $ GEO       : chr  "Helm Glacier - southern Coast Mountains (Garibaldi Provincial Park), British Columbia" "Helm Glacier - southern Coast Mountains (Garibaldi Provincial Park), British Columbia" "Helm Glacier - southern Coast Mountains (Garibaldi Provincial Park), British Columbia" "Helm Glacier - southern Coast Mountains (Garibaldi Provincial Park), British Columbia" ...
 $ MEASURE   : chr  "Annual mass balance" "Annual mass balance" "Annual mass balance" "Annual mass balance" ...
 $ Vector    : chr  "v54326054" "v54326054" "v54326054" "v54326054" ...
 $ Coordinate: num  1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 ...
 $ Value     : chr  "-1460.0" "-780.0" "-2730.0" "-940.0" ...

tapply(X = as.numeric(glacier[glacier$MEASURE == "Annual mass balance", c("Value")]), 
                      INDEX = unique(glacier[ , 2]), FUN = median, na.rm = T)

给出错误： tapply 错误（as.numeric（冰川[冰川$MEASURE == "Annual mass balance"，： аргументы должны иметь одинаковую длину 我检查了参数，它们对于 tapply 函数来说似乎很正常。不知道，怎么了。提前致谢。

编辑：

tapply(X = as.numeric(glacier[glacier$MEASURE == "Annual mass balance", c("Value")]), 
                      INDEX = glacier[ , 2], FUN = median, na.rm = T)

给出同样的错误

Answer 1

您正在尝试对冰川数据框进行子集化，我希望 glacier$Measure !="Annual mass balance" 中有一个或多个元素。因此 glacier[glacier$MEASURE == "Annual mass balance", c("Value")] 的列长度不等于 glacier[ , 2] 的长度。如果这是真的，那么您还需要对索引进行子集化。

这是一个创建数据子集以提高可读性的解决方案：

glacier <- read.csv("01530102-eng.csv", stringsAsFactors = F)

glacierreduced<-glacier[glacier$MEASURE == "Annual mass balance",]
tapply(X = as.numeric(glacierreduced$Value),  INDEX = glacierreduced[ , 2],  
       FUN = median, na.rm = T)

在这种情况下，tapply（参数长度不等）有什么问题？

What's wrong with tapply (args are unequal length) in this case?

r

tapply