I have the following if statement:
var formatCity =
obj => R.both(has('city'), has('state'))(obj) ? appendCommaToCity(obj) : obj
I would like to make this code point free, but can not figure out a way around the if statement.
That's quite simple actually using the ifElse function - or its specialisation, when:
const formatCity = R.when(R.both(has('city'), has('state')), appendCommaToCity);
Related
firstly apologies: I am a beginner in Earth Engine, but googling my question hasn't yielded any results. I have a reasonable amount of experience with other languages/platforms.
I have a table of data with headers 'name' and 'value' with N entries, I also have a multiband images in which the bands are named the same as the 'name' column in my table.
I want to apply a functions to each band in the image, based on its corresponding value in the table.
I'm struggling to find a way to do this without using loops and getInfo(), both of which I understand are not efficient and generally frowned upon.
I think perhaps I'm missing something fundamental here regarding the interaction between local variables and things occuring serverside - help would be greatly appreciated!
You could perhaps iterate over the band names in the image:
var updatedImage = ee.Image(
image.bandNames().iterate(
function (bandName, acc) {
bandName = ee.String(bandName) // Must cast from ee.Element to actual type
var feature = features
.filter(ee.Filter.eq('name', bandName))
.first()
var value = feature.getNumber('value')
var bandWithFunctionApplied = image.select(bandName)
.add(value) // Apply some function
return ee.Image(acc)
.addBands(bandWithFunctionApplied)
},
ee.Image([])
)
)
https://code.earthengine.google.com/082411908a7525a4c8a87916b5ea88fc
the problem is quite simple. We have some store with many products.
For example each item has fields (and many others):
Height
Weight
Length
Name
Color
Price
We implement some page where we can filter items by range for numbers (like price, length) and string (color).
So, the problem is here:
- we need to allow people to filter items by any of criteria above (color+price, color+length+weight).
The basic approach with predefined SELECT+WHERE is too hard to main.
Is there any other option?
Thank you.
Jonathan is right. I think using if cases would be easiest and would look something like this.
var res = _dbContextorSource.table.Where(x => x.ID > 0); //something to get all of them
//or (x => x.ID >= 0 && x.ID <= 50) if you're showing 50 on a page
if(FirstFilterIsUsed){
res = res.table.Where(x => x.FirstField == FirstFilter);
}
if(SecondFilterIsUsed){
res = res.table.Where(x => x.SecondField == SecondFilter);
}
//etc
I think you could implement a more clean solution that loops through each filter. This is super pseudo but I've used solutions like this.
var filters = GetUserFilters();
foreach(Filter filter in filters){
res = res.table.Where(x => x.GetType().
GetProperty(filter.MatchingName).GetValue(x) == filter.FilterValue);
}
var result = res.ToList();
Common Solution
The most common solution is performing a big if` case. It takes some time to support all your fields but will work great at the end.
However, if you want to do it dynamically, 2 third-party libraries can help you with this
LINQ Dynamic
https://www.nuget.org/packages/System.Linq.Dynamic.Core/
The syntax required is a little bit different from C# but work great. It's the most popular library to do such a thing.
C# Eval Expression
Disclaimer: I'm the owner of the project C# Eval Expression
The library is not free, but you can do pretty much any dynamic LINQ using the same syntax as C#.
So you will be able to build a string to evaluate and the library will do the rest for you.
Here are some example using EF Classic:
https://dotnetfiddle.net/Otm0Aa
https://dotnetfiddle.net/mwTqW7
I am trying to use the command:
audio_play_sound()
I am trying to insert it into this piece of code, so that when the player jumps, a sound plays.
if (key_jump) && (jumps > 0)
{
jumps -=1;
vsp = -jumpspeed;
}
Code that causes problem:
if (key_jump) && (jumps > 0)
{
jumps -=1;
vsp = -jumpspeed;
audio_play_sound(snd_jump)
}
Simply inserting the line into the if statement does not work, and gives the error WRONG NUMBER OF ARGUMENTS IN FUNCTION. This is rather confusing, perhaps I am using the wrong command? Thanks in advance
The problem is stated in the error, you're providing the wrong number of arguments to the audo_play_sound function.
from the docs
audio_play_sound(index, priority, loop);
As the person above states your answer is audio_play_sound(snd_jump, 1, false).
I need to know how I can parse a variable path in Flex 3 & e4X. For example, I have two XML strings where the name of one element is the only difference.
<NameOfRoot>
<NameOfChild1>
<data>1</data>
</NameOfChild1>
</NameOfRoot>
<NameOfRoot>
<NameOfChild2>
<data>2</data>
</NameOfChild2>
</NameOfRoot>
Currently I am accessing variables like this:
var data1:String = NameOfRoot.*::NameOfChild1.*::data;
var data2:String = NameOfRoot.*::NameOfChild2.*::data;
I would rather make this task more abstract so that if "NameOfChild3" is introduced I do not need to update the code. For example:
var data:String = NameOfRoot.*::{variable}.*::data;
Does anyone have insights into how this can be done?
Use the child property (LiveDocs example here):
var tagName:String = "NameOfChild1";
var data:String = NameOfRoot.child(tagName).data;
That's with no namespacing--not sure whether it's necessary in your case, but I assume you'd add some *::'s?
this also works:
var data:String = NameOfRoot..data;
but if you have more than 1 data node you'll have to sort some stuff out.
It looks like the ".*." operation will work. I wonder if this is the easiest way to handle this problem.
var data:String = NameOfRoot.*.*::data;
So I have something like this:
var xmlStatement:String = "xmlObject.node[3].#thisValue";
What mystery function do I have to use so that I can execute xmlStatement and get thisValue from that xmlObject? Like....
var attribute:String = mysteryFunction(xmlStatement);
P.S. I know eval() works for actionscript2, I need the as3 solution. :)
Unfortunately this is not possible in ActionScript 3. This however might be a solution: http://blog.betabong.com/2008/09/23/e4x-string-parser/
For your example it would be:
var attribute : String = String( E4X.evaluate( XMLList(xmlobject) , 'node[3].#thisValue' ) );