R语言-计算平均值不同函数的区别说明

> mean(x)
>         num          x1          x2          x3 
10378050.50       89.45       81.18       80.45 

> colMeans(x)
        num          x1          x2          x3 
10378050.50       89.45       81.18       80.45 
> colMeans(x)[c("x1","x2","x3")]
   x1    x2    x3 
89.45 81.18 80.45 

> apply(x, 2, mean)
        num          x1          x2          x3 
10378050.50       89.45       81.18       80.45 

> apply(x[c("x1","x2","x3")], 2, max)
 x1  x2  x3 
100  90  96 

mean(x, trim = 0, na.rm = FALSE, ...)

# Create a vector. 
x <- c(17,8,6,4.12,11,8,54,-11,18,-7)
 
# Find Mean.
result.mean <- mean(x)
print(result.mean)

[1] 10.812

# Create a vector.
x <- c(12,7,3,4.2,18,2,54,-21,8,-5)
 
# Find Mean.
result.mean <-  mean(x,trim = 0.3)
print(result.mean)

[1] 5.55

# Create a vector. 
x <- c(12,7,3,4.2,18,2,54,-21,8,-5,NA)
 
# Find mean.
result.mean <-  mean(x)
print(result.mean)
 
# Find mean dropping NA values.
result.mean <-  mean(x,na.rm = TRUE)
print(result.mean)

[1] NA
[1] 8.22

median(x, na.rm = FALSE)

# Create the vector.
x <- c(12,7,3,4.2,18,2,54,-21,8,-5)
 
# Find the median.
median.result <- median(x)
print(median.result)

[1] 5.6

# Create the function.
getmode <- function(v) {
   uniqv <- unique(v)
   uniqv[which.max(tabulate(match(v, uniqv)))]
}
 
# Create the vector with numbers.
v <- c(2,1,2,3,1,2,3,4,1,5,5,3,2,3)
 
# Calculate the mode using the user function.
result <- getmode(v)
print(result)
 
# Create the vector with characters.
charv <- c("baidu.com","tmall.com","yiibai.com","qq.com","yiibai.com")
 
# Calculate the mode using the user function.
result <- getmode(charv)
print(result)

[1] 2
[1] "yiibai.com"