Array manipulation question

[DL]

say, we have the following:

// declare an array
myArray = []; // short hand? same as myArray = new Array ?

// populate it
myArray[0] = 0;
myArray[1] = 0;
myArray[2] = 1;
myArray[3] = 0;

// now problem to solve
// fact: the above array has 4 sets of data, namely 3 zeros and 1 of
value one.
// say, the business rule is, if all set of data are of same value ( 0
|| 1), then do nothing
else alert ('hey dark sheep found').

I understand Array has a bunch of methods, but not sure which one is a
good one to solve the above problem.

Thanks.

[Erwin Moller]

DL schreef:

say, we have the following:

// declare an array
myArray = []; // short hand? same as myArray = new Array ?

// populate it
myArray[0] = 0;
myArray[1] = 0;
myArray[2] = 1;
myArray[3] = 0;

// now problem to solve
// fact: the above array has 4 sets of data, namely 3 zeros and 1 of
value one.

Hi,

Well, they do not contain a 'set' but just a plain value.

// say, the business rule is, if all set of data are of same value ( 0
|| 1), then do nothing
else alert ('hey dark sheep found').

I understand Array has a bunch of methods, but not sure which one is a
good one to solve the above problem.

No offense, but this is so basic I advise you to buy a book on
JavaScript (any will do, but O'Reilly's Definitive Guide is good).

Here follows an example to get you going.
(It can be written in many different ways, and shorter, but I hope this
version is clear to you.)

<script type="text/javascript">
var myArray = [];
// populate it
myArray[0] = 0;
myArray[1] = 1;
myArray[2] = 0;
myArray[3] = 0;

var arrLength = myArray.length;
var firstVal = myArray[0];

for(var i=0;i<arrLength ;i++){
if (myArray[i] != firstVal){
alert ("Black sheep found.");
break;
}
}
</script>

>
Thanks.

You're welcome.

Regards,
Erwin Moller

[Henry]

On May 30, 2:24 pm, Erwin Moller wrote:
<snip>

var firstVal = myArray[0];

for(var i=0;i<arrLength ;i++){
if (myArray[i] != firstVal){
alert ("Black sheep found.");
break;
}}

<snip>

You may as well start the loop counter at 1 as you already know that -
firstVal - will be equal to - myArray[i] - when - i - is zero as you
just set it to that value. (Or was that a deliberate mistake as a
learning exercise?)

[Erwin Moller]

Henry schreef:

On May 30, 2:24 pm, Erwin Moller wrote:
<snip>

>var firstVal = myArray[0];

for(var i=0;i<arrLength ;i++){
if (myArray[i] != firstVal){
alert ("Black sheep found.");
break;
}}

<snip>

You may as well start the loop counter at 1 as you already know that -
firstVal - will be equal to - myArray[i] - when - i - is zero as you
just set it to that value. (Or was that a deliberate mistake as a
learning exercise?)

Totally true Henry. A few wasted CPU cycles.

A better routine would also check for the number of array elements and
stuff like that (eg refuse if only 1 element, or refuse if 0.).

I just wanted the guy to have some material to work with, and didn't
give the code too much thought. ;-)

Regards,
Erwin Moller

[DL]

On May 30, 9:24*am, Erwin Moller
<Since_humans_r ead_this_I_am_s pammed_too_m... @spamyourself.c omwrote:

Hi,

Well, they do not contain a 'set' but just a plain value.

// say, the business rule is, if all set of data are of same value ( 0
|| 1), then do nothing
else alert ('hey dark sheep found').

I understand Array has a bunch of methods, but not sure which one is a
good one to solve the above problem.

No offense, but this is so basic I advise you to buy a book on
JavaScript (any will do, but O'Reilly's Definitive Guide is good).

Here follows an example to get you going.
(It can be written in many different ways, and shorter, but I hope this
version is clear to you.)

<script type="text/javascript">
var myArray = [];
// populate it
myArray[0] = 0;
myArray[1] = 1;
myArray[2] = 0;
myArray[3] = 0;

var arrLength = myArray.length;
var firstVal = myArray[0];

for(var i=0;i<arrLength ;i++){
* * * * if (myArray[i] != firstVal){
* * * * * * * * alert ("Black sheep found.");
* * * * * * * * break;
* * * * }}

</script>

Thanks.

You're welcome.

Regards,
Erwin Moller

No offense at all, I know it's embrassing and thanks for the book
recommendation.

[timothytoe]

On May 30, 6:03 am, DL <tatata9...@gma il.comwrote:

say, we have the following:

// declare an array
myArray = []; // short hand? same as myArray = new Array ?

// populate it
myArray[0] = 0;
myArray[1] = 0;
myArray[2] = 1;
myArray[3] = 0;

// now problem to solve
// fact: the above array has 4 sets of data, namely 3 zeros and 1 of
value one.
// say, the business rule is, if all set of data are of same value ( 0
|| 1), then do nothing
else alert ('hey dark sheep found').

I understand Array has a bunch of methods, but not sure which one is a
good one to solve the above problem.

Thanks.

Here's an interesting way. It occurred to me that the JavaScript
"some" method could be used with a bit of work...

function monoArray(arr) {
function isEqToFirst(ele ment,index,arra y) {
return (element!==arra y[0]);
}
if (arr && arr.length>0) {
return !(arr.some(isEq ToFirst));
}
}

var passed = monoArray([2,5,8,1,4]);
alert(passed); //false
passed = monoArray([12, 12, 12, 12, 12]);
alert(passed); //true
passed=monoArra y([5]);
alert(passed); //true
passed=monoArra y([]);
alert(passed); //undefined
passed=monoArra y();
alert(passed); //undefined
passed=monoArra y(5);
alert(passed); //undefined

This only works for JavaScript interpreters which have the "some"
method. See "compatibil ity" here for the code to add if you're afraid
of running into older, less capable ECMAScript implementations .

http://developer.mozilla.org/en/docs...cts:Array:some

[timothytoe]

On May 30, 5:50 pm, timothytoe <timothy...@gma il.comwrote:

On May 30, 6:03 am, DL <tatata9...@gma il.comwrote:

say, we have the following:

// declare an array
myArray = []; // short hand? same as myArray = new Array ?

// populate it
myArray[0] = 0;
myArray[1] = 0;
myArray[2] = 1;
myArray[3] = 0;

// now problem to solve
// fact: the above array has 4 sets of data, namely 3 zeros and 1 of
value one.
// say, the business rule is, if all set of data are of same value ( 0
|| 1), then do nothing
else alert ('hey dark sheep found').

I understand Array has a bunch of methods, but not sure which one is a
good one to solve the above problem.

Thanks.

Here's an interesting way. It occurred to me that the JavaScript
"some" method could be used with a bit of work...

function monoArray(arr) {
function isEqToFirst(ele ment,index,arra y) {
return (element!==arra y[0]);
}
if (arr && arr.length>0) {
return !(arr.some(isEq ToFirst));
}

}

var passed = monoArray([2,5,8,1,4]);
alert(passed); //false
passed = monoArray([12, 12, 12, 12, 12]);
alert(passed); //true
passed=monoArra y([5]);
alert(passed); //true
passed=monoArra y([]);
alert(passed); //undefined
passed=monoArra y();
alert(passed); //undefined
passed=monoArra y(5);
alert(passed); //undefined

This only works for JavaScript interpreters which have the "some"
method. See "compatibil ity" here for the code to add if you're afraid
of running into older, less capable ECMAScript implementations .

http://developer.mozilla.org/en/docs...5_Reference:Gl...

Sent too early. A more compact version of the same thing:

function monoArray(arr) {
if (arr && arr.length>0) {
return !arr.some(funct ion(element,ind ex,array) {
return element!==array[0];
});
}
}

[timothytoe]

On May 30, 6:03 am, DL <tatata9...@gma il.comwrote:

say, we have the following:

// declare an array
myArray = []; // short hand? same as myArray = new Array ?

// populate it
myArray[0] = 0;
myArray[1] = 0;
myArray[2] = 1;
myArray[3] = 0;

// now problem to solve
// fact: the above array has 4 sets of data, namely 3 zeros and 1 of
value one.
// say, the business rule is, if all set of data are of same value ( 0
|| 1), then do nothing
else alert ('hey dark sheep found').

I understand Array has a bunch of methods, but not sure which one is a
good one to solve the above problem.

Thanks.

By the way, if the only possibilities for the data are 0 and 1 (as in
your example), you could use Array.reduce to find the sum of all the
elements in the array. If the sum is zero of the length of the array,
you pass. Else you fail.

[DL]

On May 30, 9:04*pm, timothytoe <timothy...@gma il.comwrote:

On May 30, 6:03 am, DL <tatata9...@gma il.comwrote:

say, we have the following:

// declare anarray
myArray = []; // short hand? *same as myArray = newArray* *?

// populate it
myArray[0] = 0;
myArray[1] = 0;
myArray[2] = 1;
myArray[3] = 0;

// now problem to solve
// fact: the abovearrayhas 4 sets of data, namely 3 zeros and 1 of
value one.
// say, the business rule is, if all set of data are of same value ( 0
|| 1), then do nothing
else alert ('hey dark sheep found').

I understandArray has a bunch of methods, but not sure which one is a
good one to solve the above problem.

Thanks.

By the way, if the only possibilities for the data are 0 and 1 (as in
your example), you could useArray.reduce to find the sum of all the
elements in thearray. If the sum is zero of the length of thearray,
you pass. Else you fail.- Hide quoted text -

- Show quoted text -

Wow, the code of your most recent post is elegant. The data is one of
three: 0,1,2. But it looks like one-dimensional array is not good
enough to solve the problem. Too bad my local Barnes and Noble does
not carry the recommended book, can't wait.

[timothytoe]

On May 30, 6:51 pm, DL <tatata9...@gma il.comwrote:

On May 30, 9:04 pm, timothytoe <timothy...@gma il.comwrote:

On May 30, 6:03 am, DL <tatata9...@gma il.comwrote:

say, we have the following:

// declare anarray
myArray = []; // short hand? same as myArray = newArray ?

// populate it
myArray[0] = 0;
myArray[1] = 0;
myArray[2] = 1;
myArray[3] = 0;

// now problem to solve
// fact: the abovearrayhas 4 sets of data, namely 3 zeros and 1 of
value one.
// say, the business rule is, if all set of data are of same value ( 0
|| 1), then do nothing
else alert ('hey dark sheep found').

I understandArray has a bunch of methods, but not sure which one is a
good one to solve the above problem.

Thanks.

By the way, if the only possibilities for the data are 0 and 1 (as in
your example), you could useArray.reduce to find the sum of all the
elements in thearray. If the sum is zero of the length of thearray,
you pass. Else you fail.- Hide quoted text -

- Show quoted text -

Wow, the code of your most recent post is elegant. The data is one of
three: 0,1,2. But it looks like one-dimensional array is not good
enough to solve the problem. Too bad my local Barnes and Noble does
not carry the recommended book, can't wait.

I think it may be overkill for the task at hand, but you seemed
interested in learning how to use the Array methods available in
JavaScript, so I thought I'd give it a shot. Look into Array.map and
Array.reduce as well.