我在R方面比较新,我想建立一个函数,它可以循环遍历导入的表格中的列,并生成由均值和95%置信区间组成的输出。理想情况下,应该能够用不同样本大小对列进行自举,但是首先我想让迭代工作起来。我有一些好像有点用的东西,但我无法完全实现它。代码如下,包括示例数据和输出:
#cdata<-read.csv(file.choose(),header=T)#read data from selected file, works, commented out because data is provided below
#cdata #check imported data
#Sample Data
# WALL NRPK CISC WHSC LKWH YLPR
#1 21 8 1 2 2 5
#2 57 9 3 1 0 1
#3 45 6 9 1 2 0
#4 17 10 2 0 3 0
#5 33 2 4 0 0 0
#6 41 4 13 1 0 0
#7 21 4 7 1 0 0
#8 32 7 1 7 6 0
#9 9 7 0 5 1 0
#10 9 4 1 0 0 0
x<-cdata[,c("WALL","NRPK","LKWH","YLPR")] #only select relevant species
i<-nrow(x) #count number of rows for bootstrapping
g<-ncol(x) #count number of columns for iteration
#build bootstrapping function, this works for the first column but doesn't iterate
bootfun <- function(bootdata, reps) {
boot <- function(bootdata){
s1=sample(bootdata, size=i, replace=TRUE)
ms1=mean(s1)
return(ms1)
} # a single bootstrap
bootrep <- replicate(n=reps, boot(bootdata))
return(bootrep)
} #replicates bootstrap of "bootdata" "reps" number of times and outputs vector of results
cvr1 <- bootfun(x$YLPR,50000) #have unsuccessfully tried iterating the location various ways (i.e. x[i])
cvrquantile<-quantile(cvr1,c(0.025,0.975))
cvrmean<-mean(cvr1)
vec<-c(cvrmean,cvrquantile) #puts results into a suitable form for output
vecr<-sapply(vec,round,1) #rounds results
vecr
2.5% 97.5%
28.5 19.4 38.1
#apply(x[1:g],2,bootfun) ##doesn't work in this case
#desired output:
#Species Mean LowerCI UpperCI
#WALL 28.5 19.4 38.1
#NRPK 6.1 4.6 7.6
#YLPR 0.6 0.0 1.6
我也尝试过使用boot包,很好地通过均值进行迭代,但是我无法在置信区间上做到同样的效果。上面的“普通”代码还有一个优点,就是您可以轻松地检索引导结果,这些结果可能用于其他计算。为了完整起见,这是boot代码:
#Bootstrapping using boot package
library(boot)
#data<-read.csv(file.choose(),header=TRUE) #read data from selected file
#x<-data[,c("WALL","NRPK","LKWH","YLPR")] #only select relevant columns
#x #check data
#Sample Data
# WALL NRPK LKWH YLPR
#1 21 8 2 5
#2 57 9 0 1
#3 45 6 2 0
#4 17 10 3 0
#5 33 2 0 0
#6 41 4 0 0
#7 21 4 0 0
#8 32 7 6 0
#9 9 7 1 0
#10 9 4 0 0
i<-nrow(x) #count number of rows for resampling
g<-ncol(x) #count number of columns to step through with bootstrapping
boot.mean<-function(x,i){boot.mean<-mean(x[i])} #bootstrapping function to get the mean
z<-boot(x, boot.mean,R=50000) #bootstrapping function, uses mean and number of reps
boot.ci(z,type="perc") #derive 95% confidence intervals
apply(x[1:g],2, boot.mean) #bootstrap all columns
#output:
#WALL NRPK LKWH YLPR
#28.5 6.1 1.4 0.6
我已经查看了所有可以找到的资源,但似乎无法让事情顺利进行。我的输出需求是每列的加权平均值和相应的置信区间。谢谢!
boot::boot
,因为它提供了与parallel
包的集成。 - alexwhitworth