(beginner) split and process lists

@xXBrodieXxJun 16.2020

Hey wats up, im trying to split a list,using the first half process with += -=, and the second half process with the first half += -=? eg 0,1,2,10,10,10 the final list would be 22,10,-2.

i can generate the values but how would i add them? could i declare them as variables or something? im only 2 wks in so any advice is appreciated.

[code] a = [0,1,2,1,10,10,10,10,10]

a.forEach(function(item, i) { if (item == 0) a[i] += 12; if (item == 1) a[i] += 0; if (item == 2) a[i] -= -12; });[/code]

Thanks

Remark by Sempervivum: Unfortunately the forum software had eaten your “[i]“. You better use code tags when posting code: “[code]your code here[/code]“
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16 Comments(s) _↴

@JMRKERJun 16.2020 — #Can you state the nature of your problem with some other words?

I am unclear of the expected results and how they are supposed to be generated.

@xXBrodieXxauthorJun 16.2020 — #Thanks JMRKER i did seperate the array now id like to call +=12, +=0 or -=12 on each element depending on the index value of the other array eg. if (0) add12to10; if (1) add0to10; if (2) minus12from10; theres proly a better solution but im still basic.

@xXBrodieXxauthorJun 16.2020 — #i decalared >>

var x = function(){x += 12;}

var y = function(){y += 0;}

var z = function(){z -= 12;}

but im not sure how i can call a function on one array from another.Any suggestions are aprreciated.

@daveyerwinJun 16.2020 — #"Hey wats up, im trying to split a list"

We don't know what you mean by that ?

Maybe you want to make two arrays

from the array [0,1,2,1,10,10,10,10,10] ?

Anyways ...

``<i>
 </i>a = [0,1,2,1,10,10,10,10,10]
 
 a.forEach(function(item, index) {
 console.log(item, index);
 });<i>
 </i>``

run that in your browser then press F12

it will show this ...

0 0

1 1

2 2

1 3

10 4

10 5

10 6

10 7

10 8

hopefully, that will give you an idea about how forEach works

keep asking questions

we will try to guide you

@xXBrodieXxauthorJun 16.2020 — #Thanks my biggest problem was trying to impose some math from one array to another? not really sure how to format it tbh i need the state of array1 to declare what formular will be executed?

@daveyerwinJun 16.2020 — #@xXBrodieXx#1619585

" i need the state of array1 to declare what formular will be executed?"

i am hearing this

maybe Im wrong ...

you want to use the value of index 0 of array "a"

a = [0,1,2,1]

to determine which function will be called with

the value of index 0 of array "b" as the argument

b = [10,10,10,10]

(the argument is the value passed to the function)

maybe this will be more clear

let me change the example to this ...

``<i>
 </i>a = [0,1,2,1,10,10,10,10,10]
 
 a.forEach(function(value, index) {
 console.log(value, index);
 });<i>
 </i>``

run that in your browser then press F12

it will show this ...

0 0

1 1

2 2

1 3

10 4

10 5

10 6

10 7

10 8

hang in there

when we can talk to each other with the same terms

(index value argument function)

i will give you the complete code

@xXBrodieXxauthorJun 16.2020 — #Ill try explain..

Array 1 is made up of 0s 1s and 2s and Array 2 is random values from 0 to 127. Array 1 values eg -12, 0,+12 need to be added to each element of array 2, not to replace them.

My objective- If (arr1[0]=0){arr2[0]+12)} If (arr1[0]=1){arr2[0]+0)} If (arr1[0]=2){arr2[0]-12)} but i think i need variables.the array will be from 3 to 25 elements..the list is one big array but they are coming from outside js as 2 lists that are combined as one,

@daveyerwinJun 16.2020 — #<script>

arr1 = [0,1,2,0];

arr2 = [2,9,3,6];

arr1.forEach(function(value, index) {

if(value == 0){arr2[index] += 12};

if(value == 1){arr2[index] += 0};

if(value == 2){arr2[index] += -12};

});

alert(arr2);

</script>

arr2 now equals [14,9,-9,18]

"the list is one big array but they are coming from outside js as 2 lists that are combined as one"

say array if you mean array, don't say list unless you mean list

where is outside Javascript ?

@xXBrodieXxauthorJun 17.2020 — #yess of course so straight forward, i must be over thinking.Thanks DaveyErwin i was close to..

@JMRKERJun 17.2020 — #My take on the problem (based upon 'DaveyErwin's understanding example)

'

<!DOCTYPE html><html lang="en"><head><title> Test Page </title>

<meta charset="UTF-8">

<meta name="viewport" content="width-device-width,initial-scale=1.0, user-scalable=yes"/>



</head><body>

<pre id='demo'></pre>

<script>
   arr1 = [12,0,-12];
   arr2 = [2,9,3,6];
   arr3 = [0,1,2,3,4,5,6,7,8,9];
  
   function specialAdds(a, b) {
   b.forEach(function(value, index) {
   var i = index % a.length;
   b[index] += a[i];
   });
   return b;
   }
  
   document.getElementById('demo').innerHTML += 'arr1: '+arr1+'n';
   document.getElementById('demo').innerHTML += 'arr2: '+arr2+'n';
   document.getElementById('demo').innerHTML += 'arr3: '+arr3+'nn';
  //  document.getElementById('demo').innerHTML += specialAdds(arr1,arr2)+'nn';
  //  document.getElementById('demo').innerHTML += specialAdds(arr1,arr3)+'nn';
  
   document.getElementById('demo').innerHTML += Special addition of arr1 and arr2: 
 <i>    </i> ${specialAdds(arr1,arr2)}nn;
   document.getElementById('demo').innerHTML += Special addition of arr1 and arr3: 
 <i>    </i> ${specialAdds(arr1,arr3)}nn;
  </script>
  </body></html>

@xXBrodieXxauthorJun 17.2020 — #Thanks JMRKER not actually using any html,im using the js script inside Max i havent attempted any html yet.

@JMRKERJun 17.2020 — #HTML there ONLY to display results without using the alert.

It has no effect on the output of the JS function that performs the actions to display.

@xXBrodieXxauthorJun 17.2020 — #alright thanks do i call specialAdds?

@lounaxeniaJun 17.2020 — #HTML there ONLY to show results without utilizing the caution. It has no impact on the yield of the JS work that plays out the activities to appear.

@daveyerwinJun 17.2020 — #@xXBrodieXx#1619623

you don't need any HTML

I just learned what MAX8 is

I will guess you are working on

some type of tremolo or vibrato

or creating motion in the visual

display ?

@JMRKERJun 19.2020 — #@xXBrodieXx#1619623

No HTML needed, it was included just to see results without an alert.

<script>

arr1 = [12,0,-12];

arr2 = [2,9,3,6];

arr3 = [0,1,2,3,4,5,6,7,8,9];

function specialAdds(a, b) {

b.forEach(function(value, index) {

var i = index % a.length;

b[index] += a[i];

});

return b;

}

var arr12 = specialAdds(arr1,arr2);

var arr13 = specialAdds(arr1,arr3);

alert('arr1: '+arr1+'narr2: '+arr2+'n'+arr3);

alert('arr12: '+arr12+'narr13: '+arr13);

</script>

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