Calculate the average of a series

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Implementations

Assembly

Integers

Following the description for the ANSI C version, except that INT_MAX here is always 2147483647 (0x7FFFFFFF). Formatted in MASM, only returns an integer value.

avg proc
mov edx,esp
avg_loop1:
add eax,DWORD PTR [edx]
cmp DWORD PTR [edx],7fffffffh
jne avg_loop1
mov ecx,DWORD PTR [esp]
xchg esp,edx
sub edx,esp
push ecx
neg edx
shr edx,2
mov ecx,edx
xor edx,edx
sub ecx,1
div ecx
ret
avg endp

Using the FPU

This leaves the result in st(0) - caller has to free it.

avg proc
mov ecx,DWORD PTR [esp]
mov edx,esp
fldz
avg_loop1:
fild DWORD PTR [esp]
cmp DWORD PTR [esp],7fffffffh
jne avg_loop1
sub edx,esp
neg edx
shr edx,2
mov DWORD PTR [esp],edx
fild DWORD PTR [esp]
fdiv
mov DWORD PTR [esp],ecx
ret
avg endp

C

This particular function averages all integers until a INT_MAX is passed as an argument. INT_MAX is used because it is a very large number that is most likely to not be naturally part of an average. Since INT_MAX is defined by nearly all compilers, you should be able to call this function relatively easily, e.g. average(4,5,6,INT_MAX);

//stdarg.h must be included for this type of function to be declared
#include <stdarg.h>

double average( int first, ... ) {
int count = 0, sum = 0, i = first;
va_list marker;

va_start( marker, first );     /* Initialize variable arguments. */
while( i != INT_MAX )
{
sum += i;                   //increases the sum
count++;                    //increases the count
i = va_arg( marker, int);   //Gets the next argument
}
va_end( marker );              // Resets the list
return( sum ? ((double)sum / count) : 0.0 );
}

C++

#include <numeric>

template <typename Iterator>
double average(Iterator begin, Iterator end) {
return std::accumulate(begin, end, 0.0) / (end - begin);
}

Common Lisp

> (defun average (list) (/ (reduce #'+ list) (length list)))
AVERAGE
> (average '(1 2 3 4))
5/2
> (average '(1 2 3 4.0))
2.5

Erlang

average(List) ->
lists:sum(List) / length(List).

Excel

=AVERAGE([cells])

Sum a list of numbers and divide by the length of the list:

avg l = sum l / List.genericLength l

Java

This implementation can only be used with java version 1.5.0 (a.k.a java 5.0) since this new version implements varargs.

import java.util.*;

public class Averages {

public static int average(int... values) {
double sum = 0;
for (int i : values) {
if (i == Integer.MAX_VALUE) break;
sum += i;

}
return (int) Math.round(sum/(values.length-1)); //Math.round is used for rounding
}

public static void main(String[] args) {

System.out.printf("Average: %d: ", average(1,2,4,40,Integer.MAX_VALUE));

}
}

OCaml

Sum a list of integers and divide by the length of the list:

# let avg l = float(List.fold_left ( + ) 0 l) /. float(List.length l);;
val avg : int list -> float = <fun>

For example:

# avg [1;2;4;8;16];;
- : float = 6.2

Perl

use List::Util 'sum';

# Pass the list directly as the argument list
print average(1 .. 3);

sub average {
my @array = @_;
return sum(@array) / @array;
}

Python

This python function returns the average of an arbitrary sequence, a wikipedia:Generator (computer science) too:

def average(seq, total=0.0):
num = 0
for item in seq:
total += item
num += 1

If seq is sequence type such as a list or a tuple, you can calculate its average just like this:

def average(seq):
return float(sum(seq)) / len(seq)

The float() call is required to coerce the division into being a floating point, and not integer division. In python 3 all numeric divisions will be floating point divisions, and the // operator will be used to mean purely integer division.

REXX

/* Calculating average in REXX */

sum = 0.0
n = 0
do loop until figure = 0
pull figure
sum = sum + figure
n = n + 1
end do
n = n - 1
average = sum / n
say "Average =" average

Ruby

def average(sequence)
sequence.inject(:+).to_f / sequence.length
end

(Although it Ruby also knows @for ... in@, you should not use it unless you know why you're doing it.)

Scheme

(define (average list)
(/ (apply + list) (length list)))

Tcl

proc average list {expr ([join \$list +])/[llength \$list].}

or

namespace import ::tcl::mathop::*
proc average list {expr {[+ {*}\$list]/double([llength \$list])}}

Zsh

average() {
local -a array
local -F1 sum
array=({1..9})
(( sum = (\${(j:+:)array}.0) / \${(w)#array} ))
print "\$sum"
}