[RESOLVED] How To Pick Out Array Values & Sum Them?

anevins

Hi all,

What I'm trying to do is get the average of sentiment values for each City in the UK.
I have an array of all the cities in the UK, with sentiment values for each city.

-- Tricky to say, sorry --
Cities can appear more than once, so I want to find the average sentiment for that city, then construct/ return an array with just those cities and their sentiment (that has been averaged for all occurrences of that city).

This is an excerpt of my array

array (size=1871)
  0 => 
        array (size=2)
          'name' => string 'Cardiff' (length=7)
          'sentiment' => string '2.72' (length=4)
  1 => 
        array (size=2)
          'name' => string 'London' (length=6)
          'sentiment' => string '4.24' (length=4)
  2 => 
        array (size=2)
          'name' => string 'Birmingham' (length=10)
          'sentiment' => string '3.415' (length=5)
  3 => 
        array (size=2)
          'name' => string 'Birmingham' (length=10)
          'sentiment' => string '3.34' (length=4)

and so forth.

With Birmingham, for example, I want to add up 3.415 with 3.34, divide by 2 and then return just the one occurrence of "Birmingham" and its averaged sentiment. I want to do this for each city, so there is only one occurrence for each city, in another array.

Does anyone know how I might go about this?

bradgrafelman

What I would do is form a new multidimensional array where the city name is the key and the value is an array of strings-converted-to-numbers. For example, you'd loop over your array above and store the data like:

$new_array[$city_name][] = floatval($sentiment);

Then you'd simply use [man]array_sum/man on each of those new city arrays.

anevins

YES!

Thanks so much!🙂

bradgrafelman

One last thing... note that the new array you'd form as I suggested above would only need to be done in that way if you also want to have the individual values grouped together.

If you only care about the sum, then you could simply make the values in the "new_array" be the running total (sum), e.g. you'd instead have:

$new_array[$city_name] += floatval($sentiment);

Either way, don't forget to mark this thread resolved (if it is) using the link on the Thread Tools menu above.

anevins

The new that you first told me to construct was what I wanted to construct. Thanks.