start_with_x <- str_detect(words, "^x")end_with_x <- str_detect(words, "x$")words[start_with_x | end_with_x]

isTwoFactor <- function(x){
count = 0
tmp1 <- c()
tmp2 <- c()
for (i in 1:(x/2)) {
if(isPrime(i)&isPrime(x-i))
{
tmp1 <- c(tmp1,i)
tmp2 <- c(tmp2,x-i)
count <- count+1
}
}
if(count<=2&&count>0){
for (j in 1:count) {
writeLines(paste(x,"=",tmp1[j],"+",tmp2[j]))
}
}
}

看得见

sample <- rnorm(1000,mean=5,sd=10)
confint <- function(x,sample){
half_alpha <- qt(0.025,df=999)
conf_int <- mean(sample)+(sd(sample))/sqrt(1000)*c(half_alpha,-half_alpha)
if_include<- ifelse(conf_int[1]<x&conf_int[2]>x,TRUE,FALSE)
return(if_include)
}
library(tidyverse)
a <- map_lgl(sample,~confint(.x,sample))
sum(a)