This is probably a simple question for people familiarized with the Code Editor of Google Earth Engine (https://code.earthengine.google.com/) or generally Javascript.
In my code, I need to use the size of an object for a boolean conditional (e.g. n>0). However, the output of .size() which I would store in n does not return a plain integer, but a ee.Number structure and I am not being able to transform it into an integer to properly evaluate the conditional.
Example with the structure ee.Number of Earth Engine:
var n=ee.Number(1)
print(n)
print(n.int())
print(n==1)
print(n===1)
print(n.int()==1)
print(n.int()===1)
print(n.int()== parseInt(1))
This outputs these evaluate as false, even when I try to tast the number structure into an int.
1
1
false
false
false
false
false
note:
print(typeof n)
returns an object (JSON):
object
Any help very much appreciated. Thanks
This is due to how GEE works. Processing steps are constructed locally as objects and then only evaluated by the server once another function requires it.
print is one of the functions that requires execution, this is why it shows as integer in your console.
You can force evaluation with .getInfo()... this however should be used with caution, because everything is pulled to the client side, which can be problematic with big objects.
So this works:
var n=ee.Number(1)
print(n)
print(n.getInfo()==1)
giving
1
true
This section of the documentation explains the background.
If the value of n indeed is JSON, try to parse it:
n = JSON.parse(n);
Then convert it into an integer:
n = parseInt(n);
Related
Ho to evaluate a scientifc expression (x+3x-4+sin x) by passing different values x to find the output
Please let me know the inbuilt function that can be used in java
Well I am not going give the whole code to you, but here are some hints:
The best way to eval an expression without any external API would be using running the expression as a javascript code and get the result.
Since you just can't do sin(0) + 6 in javascript, you will have to use RegEx to replace all function name to Math.(function name here) without affecting other function name. Such as sin(0) + asin(0)will be replaced to Math.sin(0) + Math.asin(0).
The changing value of x is very simple, just use RegEx to replace the x to a value without affecting other stuff, like x + exp(1) will be turned to 0 + Math.exp(1)
User can run javascript code with your calculator if using javascript, please be careful not to allow users to do so.
Similar question have been asked before, you might want to take a look about it: Evaluating a math expression given in string form
You’re looking for the sin method present in the Math library.
An example:
Math.sin(25); // Returns ‘sin’ of the value ‘25’
When doing this:
casperjs somescript.js --number=736280854938322517687376855643288785
and in the code:
var casper = require('casper').create();
var value = casper.cli.get("number");
console.log(value); // yields: 7.3628085493832246e+35
// want: 736280854938322517687376855643288785
I've looked and looked, pondered and hacked, but I'm not having much luck. The easy solution seems to be simply converting the number into a string. Or passing the number in as a string. But the syntax for this eludes me.
See Raw parameter values:
By default, the cli object will process every passed argument & cast them to the appropriate detected type[...]
You need to use casper.cli.raw.get("number") to get a non-parsed value. Since integer values that are bigger than 253 cannot be represented as an integer without losing precision, you would need to work with them as a string or use some big integer library (such as JSBN).
I believe in javascript, arrays have a ".count" property. However, I believe that when writing Parse cloud code, effectively you cannot use this since .count is in a word, used by Parse (for queries).
(1) Is that correct, and is the reason I gave correctly stated or a shambles?
I believe (it seems to work) you can go ahead and use .length in Parse cloud code for the length of an array; but I'm confused "why" since javascript doco says .length
(2) Is that correct - if so why can it be done?
You inevitably use "underscore" library in Parse projects; in fact does that library offer a way to get the size/length/count of an array?
(3) Is there yet another way, using _ ?
I swear I have seen Parse cloud code using "size" (something or other like that) in relation to arrays;
(4) Is there an idiom using something like 'size' ?
Finally, indeed, considering this typical example of using _,
Parse.Cloud.afterSave("Employee", function(request)
{
var company = request.object.get("company");
var query = new Parse.Query("Employee");
query.equalTo("company", company);
query.include("company");
var justEmails = new Array();
query.each(function(employee)
{
var thatEmail = employee.get("email");
justEmails.push(thatEmail);
}
).then(function()
{
var kount = justEmails.length;
console.log(">>> count is " + kount );
justEmails = _.uniq(justEmails);
kount = justEmails.length;
console.log(">>> but count is now " + kount );
});
});
(5) is there a way to do that in "one line", saying something like _.uniq(justEmails).sizeOrWhateverTheHell();
Finally in summary,
(6) what then is the best and most sensible and most idimoatic way to get simply the length of an array, in javascript in the Parse cloud code milieu -- is it indeed .length?
There is no such thing as count. Arrays (and strings) have a .length property. Use it.
I have no idea what this is asking.
No, use .length.
See 3
_.uniq(whatever).length
See 1
It's just JavaScript.
You are correct and the best way to get the number of elements of an array in javascript (and in Parse cloud code) is to use array.length
Length is the property of the array, whereas size is a function that's defined in some javascript frameworks. Always use the length property to get the number of elements in an array.
I got a piece of code like this:
var password = eval(function(p,a,c,k,e,d){e=function(c){return(c<a?"":e(parseInt(c/a)))+((c=c%a)>35?String.fromCharCode(c+29):c.toString(36))};if(!''.replace(/^/,String)){while(c--)d[e(c)]=k[c]||e(c);k=[function(e){return d[e]}];e=function(){return'\\w+'};c=1;};while(c--)if(k[c])p=p.replace(new RegExp('\\b'+e(c)+'\\b','g'),k[c]);return p;}('9 5$=["\\8\\3\\4\\3\\2\\2\\1\\3\\2\\3\\3\\2\\2\\7\\3\\1\\4\\1\\3\\2\\1\\3\\1\\3\\2\\2\\2\\1\\3\\4\\1\\3\\2\\1\\4\\1\\3\\2\\1\\4\\1\\3\\2\\2\\1\\3\\4\\1\\3\\2\\1\\4\\1\\3\\2\\1\\4\\1\\3\\2\\1\\4\\1\\3\\2\\1\\4\\1\\3\\2\\1\\4\\1\\3\\2\\2\\1\\3\\1\\3\\2\\2"];6 c(){e["\\f\\g\\d\\a\\b"](5$[0])}',17,17,'|x2b|x5d|x5b|x21|_|function|x29|x28|var|x72|x74|O0|x65|window|x61|x6c'.split('|'),0,{}));
And I unpacked the following code(except 'var password = '):
eval(function(p,a,c,k,e,d){e=function(c){return(c<a?"":e(parseInt(c/a)))+((c=c%a)>35?String.fromCharCode(c+29):c.toString(36))};if(!''.replace(/^/,String)){while(c--)d[e(c)]=k[c]||e(c);k=[function(e){return d[e]}];e=function(){return'\\w+'};c=1;};while(c--)if(k[c])p=p.replace(new RegExp('\\b'+e(c)+'\\b','g'),k[c]);return p;}('9 5$=["\\8\\3\\4\\3\\2\\2\\1\\3\\2\\3\\3\\2\\2\\7\\3\\1\\4\\1\\3\\2\\1\\3\\1\\3\\2\\2\\2\\1\\3\\4\\1\\3\\2\\1\\4\\1\\3\\2\\1\\4\\1\\3\\2\\2\\1\\3\\4\\1\\3\\2\\1\\4\\1\\3\\2\\1\\4\\1\\3\\2\\1\\4\\1\\3\\2\\1\\4\\1\\3\\2\\1\\4\\1\\3\\2\\2\\1\\3\\1\\3\\2\\2"];6 c(){e["\\f\\g\\d\\a\\b"](5$[0])}',17,17,'|x2b|x5d|x5b|x21|_|function|x29|x28|var|x72|x74|O0|x65|window|x61|x6c'.split('|'),0,{}));
Then I got:
var _$ = ["\x28\x5b\x21\x5b\x5d\x5d\x2b\x5b\x5d\x5b\x5b\x5d\x5d\x29\x5b\x2b\x21\x2b\x5b\x5d\x2b\x5b\x2b\x5b\x5d\x5d\x5d\x2b\x5b\x21\x2b\x5b\x5d\x2b\x21\x2b\x5b\x5d\x2b\x21\x2b\x5b\x5d\x5d\x2b\x5b\x21\x2b\x5b\x5d\x2b\x21\x2b\x5b\x5d\x2b\x21\x2b\x5b\x5d\x2b\x21\x2b\x5b\x5d\x2b\x21\x2b\x5b\x5d\x2b\x21\x2b\x5b\x5d\x5d\x2b\x5b\x2b\x5b\x5d\x5d"];
function O0() {
window["\x61\x6c\x65\x72\x74"](_$[0])
}
And after decoding:
var _$ = ["([![]]+[][[]])[+!+[]+[+[]]]+[!+[]+!+[]+!+[]]+[!+[]+!+[]+!+[]+!+[]+!+[]+!+[]]+[+[]]"];
function O0() {
window["alert"](_$[0])
}
Now I wonder how the codes execute and what is the value of password ?
Thanks so much.
The code is obfuscated and intended to permit execution of arbitrary code even if the script text is passed through filters.
The approach is often used for tracking, phishing and other undesirable activities, so I would suggest you don't try running it.
All you need to do is run this code -- not the 'window' stuff, but only the 'decode' part -- and you'll see the solution.
Here are some pointers on decoding:
the outer array brackets are a decoy
an empty array [] evaluates to 0 when used in a calculation such as +[]
!0 = 1
!+0 evaluates to true or 1, !+1 to false or 0 (this surely must be a loophole in Javascript)
.. so !+[] is simply 1.
[1]+[1] is not a valid math sum, so both arrays are converted to strings before being added up.
The above takes care of the numbers. Where does the first character come from? The first part ([![]]+[][[]]) evaluates directly to a string two constants, which add together as a string again, and the array index after it picks up a single character.
This is a follow up question to this:
Google Analytics Event Tracking via a jQuery plugin
Matt Austin was correct. I was passing a string of the integer for the GA value parm when I should have been passing the int value itself. Evidently Google Analytics is sensitive like that :)
So I changed: parmValidatedObject[key] = val;
to: parmValidatedObject[key] = val.valueOf();
But that doesn't seem to be working as expected. GA doesn't seem to pick this up as an int. What am I not understanding about valueOf()?
btw, I might also run into something similar with one of the other parms that's a boolean. I'm translating those strings to the value or 0 or 1 but I'm wondering (out loud and in advance) if that's the right approach.
parseInt(val,10); will convert your string to an integer. It is a JavaScript function, not jQuery.
!!val converts a value to a boolean. Note that "0" is considered a truthy value and so !!"0" returns true, unlike the false you might expect. In this case, you may be better off using
(""+val == "0") ? false : true;