代码说明

R-fun-huangshun.R的展示

代码实现

#1 #### a<-data.frame (a1=c(2,4,6),a2=c(3,5,8),a3=c(4,1,9)) head(a)

?pmin pmin(a\(a1,a\)a2,a$a3)

apply(a,1,min)

#1.4 老师这题不会，不太理解“自定义名为…的一个函数” ##### ##方法一#### a<-data.frame (a1=c(2,4,6),a2=c(3,5,8),a3=c(4,1,9)) result<-numeric(nrow(a)) ###result初始化数据？ for(i in 1:nrow(a)) { ###for循环
result[i]<-min(a[i, ]) } print(result) ###输出为0 0 0，为啥呢

##方法二 自定义函数？#### pmin_for<-funtion(a){ row_num<-nrow(a) result<-numeric(row_num) for (i in 1:row_num) {result(i)<- min(a[i, ])

}return(result) } a <- data.frame( a1 = c(2, 4, 6), a2 = c(3, 5, 8), a3 = c(4, 1, 9)) cat(“pmin_for(a)的结果：”) print(pmin_for(a))

##方法三#### a<-data.frame (a1=c(2,4,6),a2=c(3,5,8),a3=c(4,1,9)) row_num<-nrow(a) result<-numeric(row_num) for (i in 1:row_num) { result(i)<-min(a[i, ]) }

#1.5#####

#2##### ##2.1##### b1<-data.frame( name=c(“文”, “颜”, “唐”, “黄”), score = c(95, 96, 97, 98) ) head(b1)

b2<-data.frame( name=c(“文”, “颜”), github=c(“uuu1016”, “yanyutong111”) ) head(b2)

##2.2##### ?merge

print(merged_data) merged_inner <- merge(b1, b2, by = “name”) print(merged_inner)

##2.3 ， 2.4#### merged_data <- b1 %>% inner_join(b2, by = c(“name”)) print(merged_data)