如何檢測數據框的列中的異常值？中的R

我有一個數據幀，假設這樣的：如何檢測數據框的列中的異常值？中的R

names<-c("a","a","a","a","a","b","b","b","b","b","c","c","c","c","c","c","c","c") 
var1<-c(0.942999593,0.935507266,0.973589623,0.969415912,0.95230801,0.935507266,0.888740961,0.91750551,0.944482672,0.945468585,1.457579147,0.922206277,0.941511433,0.954724791,0.941014244,0.941511433,0.941511433,1.50511433) 
var2<-c(-0.012678088,0.014313763,0.001138275,-0.020568206,0.012987126,0.001217192,0.03360358,0.009758172,0.015066932,-0.037879492,0.020471157,0.010738162,0.010952531,0.019377213,0.027140572,0.031116892,-0.018530676,-8.90E-05) 
as.data.frame(cbind(names,var1,var2))->df

我想異常值與Na轉換中的列VAR1和VAR2。不過，我想要爲「名稱」列中的每個類別獨立計算異常值。所以var1中的「a」的異常值將是var1中前5行的異常值。

我檢測異常值的方式是所有值，低於或高於分位數0.25和0.75。

有沒有簡單的方法來做到這一點在R？

非常感謝你提前。

Tina。

來源

2013-04-18 user18441

你可以通過變量'names'在你的'df'上使用'split（）'並檢測你的外層（不過你可以定義它）。 –

@JuliánUrbano：它怎麼會沒有？她要求的是分位數值，而不是絕對數值 –

@CarlWitthoft right..didn't read that right;） –

這裏是你如何能爲VAR1做到這一點：

quantiles<-tapply(var1,names,quantile) 
minq <- sapply(names, function(x) quantiles[[x]]["25%"]) 
maxq <- sapply(names, function(x) quantiles[[x]]["75%"]) 
var1[var1<minq | var1>maxq] <- NA

重複相同的VAR2（或DF $ VAR2）。

來源

2013-04-18 18:32:41

我要說的是，但這是更清潔的（注意'minq'方便的方式匹配關卡）。 –

非常感謝！ – user18441

如何檢測數據框的列中的異常值？中的R

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