Bootstrap重采样

Question

我正在尝试使用以下代码进行引导重采样。我从http://spark.rstudio.com/ahmed/bootstrap/获得了这段代码。我想使用我的数据集从网站上绘制相同的图。data1和data2是只包含一列的文本文件。

a = read.table("/home/Desktop/data1.txt")
b = read.table("/home/Desktop/data2.txt")
diff.observed = mean(b) - mean(a)
Warning messages:
1: In mean.default(b) : argument is not numeric or logical: returning NA
2: In mean.default(a) : argument is not numeric or logical: returning NA
> diff.observed 
[1] NA

我没有得到观察到的数据集的平均值。

alpha = 0.05

# Number of replicates
n = 1000

# Difference between means of bootstrapped datasets (n replicates)
diff.bootstrap = NULL

for (i in 1 : n) {
    # Sample with replacement
    a.bootstrap = sample  (a, length(a), TRUE)
    b.bootstrap = sample  (b, length(b), TRUE)

    diff.bootstrap[i] = mean(b.bootstrap) - mean(a.bootstrap)
}
 plot(density(a.bootstrap))
 plot(density(b.bootstrap))
 plot(density(diff.bootstrap))
Error in density.default(diff.bootstrap) : 'x' contains missing values

我不明白这是什么错误。您的建议将不胜感激！

Answer 1

您可以将数据加载到matrix中，然后mean就可以工作了：

a = as.matrix(read.table ("data1.txt"))
b = as.matrix(read.table ("data2.txt"))
diff.observed = mean(b) - mean(a)