Adding values together based on their position in PHP - php

Question

Each number has a corresponding value with it. There are many numbers which I can demonstate in a table here with their appropriate values:
[N] [V] N=Number V=Value
2 19
4 19
6 19
8 21
10 21
12 22
14 23
16 23
18 23
20 33
22 37
24 42
26 45
28 48
30 50
32 55
34 61
36 66
38 72
40 78
42 155
44 179
46 202
48 233
50 360
There is a process that a user will go through where they go from Number x to Number y. The values inbetween those numbers need to get added together. So for example, let's say a user goes from 16 to 38:
[N] [V] N=Number V=Value
2 19
4 19
6 19
8 21
10 21
12 22
14 23
[16][23]--
18 23 |
20 33 |
22 37 |
24 42 |
26 45 |
28 48 |---- All of these values get added together
30 50 |
32 55 |
34 61 |
36 66 |
[38][72]--
40 78
42 155
44 179
46 202
48 233
50 360
So the users total value would equal be:
23 + 23 + 33 + 37 + 42 + 45 + 48 + 50 + 55 + 61 + 66 + 72
Total Value = 555
The problem is, is that I have no idea how I to put this together in code. Like how to assign these values to their specific number and how to add those specific values together to get me a result. In PHP I simply do not know where to begin with this.
Also, the approximate values from the numbers can be represented by this equation:
v = 11.218e^(0.057n)
I would imagine this would be useful in making this whole process easier but I am still not sure how to go about implementing all of this. Any help would be very much apprieciated!

Answer 1

Put each each number with it's corresponding value into an array making number as key and value pair like this.
<?php
$arr = array(
2=> 19,
4=> 19,
6=> 19,
8=> 21,
10=> 21,
12=> 22,
14=> 23,
16=> 23,
18=> 23,
20=> 33,
22=> 37,
24=> 42,
26=> 45,
28=> 48,
30=> 50,
32=> 55,
34=> 61,
36=> 66,
38=> 72,
40=> 78,
42=> 155,
44=> 179,
46=> 202,
48=> 233,
50=> 360,
);
?>
Loop array with foreach loop like this
<?php
$sum = 0;
foreach($arr as $k => $v) {
if($k >= 16 && $k <= 38)
$sum += $v;
}
?>
There is another way using for loop statement, put both number in two separate array ($n and $v). Iterate the loop of the first array($n) and find the value from second array($v) through the index number of first array. But both array count should have same.
Example-
<?php
$n = array(2,4,6,8,10,12,14,16,18,20);
$v = array(19,19,19,21,21,22,23,23,23,33);
$sum = 0;
for($i=0, $i<count($n); $i++) {
if($n[$i] >= 16 && $n[$i] <= 38)
$sum += $v[$i];
}
?>

Answer 2

You would put your number and value pairs into an key / value array. So a shortened version of your test data would look like this:
$myDataStore = array(
"2" => "19",
"4" => "19",
"6" => "19",
"8" => "21",
"10" => "21",
"12" => "22",
"14" => "23",
"16" => "23",
"18" => "23",
"20" => "23"
);
Now you need a function to calculate your sum given a range as defined by starting and ending numbers.
function getRangeTotal($array, $startNumber, $endNumber){
$total = 0;
foreach($array as $key => $value){
if($key >= $startNumber && $key <= $endNumber){
$total = $total + $value;
}
}
return $total;
}
If you run the above function
getRangeTotal($myDataStore, 6, 12);
You'll get 83

Answer 3

Here is how you can do this using foreach
// first store you data to an array.
$kv = array(
2 => 19, 4 => 19, 6 => 19, 8 => 21,
10 => 21, 12 => 22, 14 => 23, 16 => 23,
18 => 23, 20 => 33, 22 => 37, 24 => 42,
26 => 45, 28 => 48, 30 => 50, 32 => 55,
34 => 61, 36 => 66, 38 => 72, 40 => 78,
42 => 155, 44 => 179, 46 => 202,48 => 233,
50 => 360
);
$start = 16;
$end = 32;
$sum = 0; //variable to keep sum
$n = 0; //variable to keep count
//loop through the array
foreach ($kv as $k => $v){
if ($k >=$start && $k <= $end){ //if key is in your range
$sum += $v; //add value to sum
$n ++; // increment count
}
}
$v = 11.218*pow(M_E,0.057*$n); //calculate the approximate values
echo "$sum\n$v\n";
Also refer to : pow and Predefined Constants