1.I have this array and i want to extract only the "rate" values.
I want y Array to look like this
array = [6,355.1675 , 4,826.3112 , 5,429.8488]
[{
code = USD;
description = "United States Dollar";
rate = "6,355.1675";
"rate_float" = "6355.1675";
symbol = "$";
}, {
code = GBP;
description = "British Pound Sterling";
rate = "4,826.3112";
"rate_float" = "4826.3112";
symbol = "£";
}, {
code = EUR;
description = Euro;
rate = "5,429.8488";
"rate_float" = "5429.8488";
symbol = "€";
}]
It looks like you have JSON that contains an array of dictionaries.
Write some code that:
Decodes the JSON into native objects. At the simplest it would be converted to an array of dictionaries.
You could then write code that loops through the array, extracts the rate value for each array entry, and prints it.
As others have said, you could do this with a map statement, but if you're new to programming then the for loop approach is easier to understand.
If you array is called array, then you can do it this way:
array.map { print ($0["rate"] }
Related
The problem with the ECMA standard for sort of Object.keys() is known:
Object.keys() handle all keys with integer (example: 168), including integer as strings (example: "168"), as a integer. The result is, both are the same (168 === "168"), and overwrite itself.
var object = {};
object["168"] = 'x';
object[168] = 'y';
Object.keys(object); // Array [ "168" ]
object[Object.keys(object)]; // "y"
Interestingly, all keys (including pure integer keys) are returned as a string.
The ecma262 wrote about this: All keys will be handle as a integer, expect the key is a String but is not an array index.
https://tc39.es/ecma262/#sec-ordinaryownpropertykeys
That should tell us: 168 === "168". A toString() do not solve the problem.
var object = {};
object[[3].toString()] = 'z';
object[[1].toString()] = 'x';
object[[2].toString()] = 'y';
Object.keys(object);
// Array(3) [ "1", "2", "3" ]
Paradoxically, in this case, only integer apply as "enumerable" (it's ignoring array.sort(), that sort also strings with letters.).
My question about this is simple: How can i prevent the sort function in Object.keys()? I have testet the Object.defineProperties(object, 1, {value: "a", enumerable: true/false}), but that mean not realy enumerable in the case of integer or string or integer-like string. It means only should it be counted with or not. It means "counted" like omit (if it false), not "enumerabled" like ascending or descending.
A answere like that is not a good answer: Please use only letters [a-zA-Z] or leastwise a letter at the first position of keyword.
What I want: That the keys are not sorted, but output in the order in which they were entered, whether integer, string or symbol.
Disclaimer: Please solutions only in JavaScript.
Javascript Objects are unordered by their nature. If you need an ordered object-like variable I would suggest using a map.
To achieve what you're looking for with a map instead of object you'd do something like the below:
var map1 = new Map();
map1.set("123", "c");
map1.set(123, "b");
var iterator1 = map1.keys();
var myarray = [];
for (var i = 0; i < map1.size; i++) {
myarray.push(iterator1.next().value);
}
console.log(myarray);
// Array ["123", 123]
Unfortunately it's not compatible with IE and I'm not sure how else you could achieve what you need without it. A quick Google did return something about jQuery maps, though.
If you don't want to use jQuery and still need to support IE some points are below:
Is there anything stopping you using an array rather than JS object to store the data you need? This will retain the order per your requirements unlike objects. You could have an object entry in each iteration which represents the key then use a traditional foreach to obtain them as an array. I.e.
The array:
var test_array = [
{key: 123, value: 'a value here'},
{key: "123", value: 'another value here'}
];
// console.log(test_array);
Getting the keys:
var test_array_keys = [];
test_array.forEach(function(obj) { test_array_keys.push(obj['key']); } );
// console.log(test_array_keys);
Then if you needed to check whether the key exists before adding a new entry (to prevent duplicates) you could do:
function key_exists(key, array)
{
return array.indexOf(key) !== -1;
}
if(key_exists('12345', test_array_keys))
{
// won't get here, this is just for example
console.log('Key 12345 exists in array');
}
else if(key_exists('123', test_array_keys))
{
console.log('Key 123 exists in array');
}
Would that work? If not then the only other suggestion would be keeping a separate array alongside the object which tracks the keys and is updated when an entry is added or removed to/from the object.
Object Keys sorted and store in array
First Creating student Object. then sort by key in object,last keys to store in array
const student={tamil:100, english:55, sci:85,soc:57}
const sortobj =Object.fromEntries(Object.entries(student).sort())
console.log(Object.keys(sortobj))
use map instead of an object.
let map = new Map()
map.set("a", 5)
map.set("d", 6)
map.set("b", 12)
to sort the keys (for example, to update a chart data)
let newMap = new Map([...map.entries()].sort())
let keys = Array.from(newMap.keys()) // ['a','b','d']
let values = Array.from(newMap.values()) // [5,12,6]
If I have the following array and I want to create a string array containing the door prizes by mapping the mysteryDoors array as keys for the dictionary, and get the corresponding values into a new array.
Thus I would get a string array of ["Gift Card", "Car", "Vacation"] how can I do that?
let mysteryDoors = [3,1,2]
let doorPrizes = [
1:"Car", 2: "Vacation", 3: "Gift card"]
You can map() each array element to the corresponding value in
the dictionary. If it is guaranteed that all array elements are
present as keys in the dictionary then you can do:
let mysteryDoors = [3, 1, 2]
let doorPrizes = [ 1:"Car", 2: "Vacation", 3: "Gift card"]
let prizes = mysteryDoors.map { doorPrizes[$0]! }
print(prizes) // ["Gift card", "Car", "Vacation"]
To avoid a runtime crash if a key is not present, use
let prizes = mysteryDoors.flatMap { doorPrizes[$0] }
to ignore unknown keys, or
let prizes = mysteryDoors.map { doorPrizes[$0] ?? "" }
to map unknown keys to a default string.
If you have to use map, then it would look something like the following:
let array = mysteryDoors.map { doorPrizes[$0] }
After re-reading the Apple Doc example code and changing it to what I need. I believe this is it (Almost). Unfortunately it is now in string format with new lines...
let myPrizes = doorPrizes.map { (number) -> String in
var output = ""
output = mysteryDoors[number]!
return output;
}
I'm trying to pass two arguments into a script that looks through arrays with a lot of values.
Basically, I have a pretty big JSON file with around 15 arrays (google sheet data). I then want to take the 1st argument, which is one/multiple words and match it in the 1st array. And then I want to take index numbers in the 1st array and only look through those index numbers in the 2nd array for a string that matches the 2nd argument and return the strings and the index number for future use. For example:
sheetData = [ [ "1stArray", "other", "other" ], [ "2ndArray", "stuff", "2stuff", "stuff" "2stuff" ] ]
If I then would type in: node index.js other 2stuff. It is supposed to find the two "other" entries in the 1st array, then look at the "stuff" and the first "2stuff" in the 2nd array and then return both "2stuff" and the index number 2.
So far I've been able to find one of the strings matching the 1st argument in the 1st array, but not the other ones. Nor have I been able to even go through the 2nd array trying to find another string. Here is the code I've written so far for this:
let fs = {
help: config.help.failstack,
func: (client, message, args) => {
// E = Enhance, R = Repair/replace, D = re-enhance (degrade part),
let itemName = args[0];
let enhanceWanted = args[1];
debugger;
var a = sheetData.values[[0]];
var sheetItemName = a.indexOf(itemName);
if (sheetItemName === -1) {
message.reply('Command not formatted correctly.')
.then(msg => console.log())
.catch(console.error);
} else {
var sheetFailstack = a.indexOf(enhanceWanted);
message.reply()
.then(msg => console.log(`${msg}`))
.catch(console.error);
}
}
}
var sheetFailstack = a.indexOf[enhanceWanted];
should be:
var sheetFailstack = a.indexOf(enhanceWanted);
i have a struct array that i want "break up" into smaller arrays that can be called as needed or at least figure out how i can map the items needed off one text value.
the struct:
struct CollectionStruct {
var name : String
var description : String
var title : String
var image : PFFile
var id: String
}
and the array made from the struct
var collectionArray = [CollectionStruct]()
var i = 0
for item in collectionArray {
print(collectionArray[i].name)
i += 1
}
printing partArray[i].name gives the following result:
pk00_pt01
pk00_pt02
pk00_pt03
pk01_pt01
pk01_pt02
pk01_pt03
pk01_pt04
pk01_pt05
pk01_pt06
pk01_pt07
pk01_pt08
this is just some test values but there could be thousands of entries here so i wanted to filter the entire array just by the first 4 characters of [i].name i can achieve this by looping through as above but is this achievable using something like .map?
I wanted to filter the entire array just by the first 4 characters of
[i].name
You can achieve this by filtering the array based on the substring value of the name, as follows:
let filteredArray = collectionArray.filter {
$0.name.substring(to: $0.name.index($0.name.startIndex, offsetBy: 4)).lowercased() == "pk00"
// or instead of "pk00", add the first 4 characters you want to compare
}
filteredArray will be filled based on what is the compared string.
Hope this helped.
If you want to group all data automatically by their name prefix. You could use a reducer to generate a dictionary of grouped items. Something like this:
let groupedData = array.reduce([String: [String]]()) { (dictionary, myStruct) in
let grouper = myStruct.name.substring(to: myStruct.name.index(myStruct.name.startIndex, offsetBy: 4))
var newDictionart = dictionary
if let collectionStructs = newDictionart[grouper] {
newDictionart[grouper] = collectionStructs + [myStruct.name]
} else {
newDictionart[grouper] = [myStruct.name]
}
return newDictionart
}
This will produce a dictionary like this:
[
"pk00": ["pk00_pt01", "pk00_pt02", "pk00_pt03"],
"pk01": ["pk01_pt01", "pk01_pt02", "pk01_pt03", "pk01_pt04", "pk01_pt05", "pk01_pt06", "pk01_pt07"],
"pk02": ["pk02_pt08"]
]
Not sure if i am understanding you correctly but it sounds like you are looking for this...
To create a new array named partArray from an already existing array named collectionArray (that is of type CollectionStruct) you would do...
var partArray = collectionArray.map{$0.name}
this may be a simple question, yet I haven't been able to find an answer to it:
How do I add a value to an array without overwriting (all) old values, or having to rewrite them? Is there such a thing as array_push in LUA? And if so, does it work for multidimensional arrays as well?
Example:
Array={"Forest","Beach","Home"} --places
Array["Forest"] = {"Trees","Flowers"} --things you find there
Array["Forest"]["Trees"] = "A tree is a perennial woody plant" --description
If I'd like to add a description of a new thing in a new place, I can't do it using
Array["Restaurant"]["Spoon"] = "A type of cutlery."
because I'd have to declare all these things, as well as the old ones so I don't overwrite them. So I'm looking for something like:
array_push(Array, "Restaurant")
array_push(Array["Restaurant"],"Spoon")
Array["Restaurant"]["Spoon"] = "A type of cutlery."
Thanks!
The following index metamethod implementation should do the trick.
local mt = {}
mt.__index = function(t, k)
local v = {}
setmetatable(v, mt)
rawset(t, k, v)
return v
end
Array={"Forest","Beach","Home"} --places
setmetatable(Array, mt)
Array["Forest"] = {"Trees","Flowers"} --things you find there
Array["Forest"]["Trees"] = "A tree is a perennial woody plant" --description
Array["Restaurant"]["Spoon"] = "A type of cutlery."
Note that you are mixing array indexed values with with string indexed values, and I don't think you intended to do so. For example, your first line stores "Forest" under the key "1", while the second line creates a new table key "Forest" with a table value that holds sequential string values. The following code prints out the generated structure to demonstrate my meaning.
local function printtree(node, depth)
local depth = depth or 0
if "table" == type(node) then
for k, v in pairs(node) do
print(string.rep('\t', depth)..k)
printtree(v, depth + 1)
end
else
print(string.rep('\t', depth)..node)
end
end
printtree(Array)
Next is the resulting output of the two code snippets listed above.
1
Forest
2
Beach
3
Home
Restaurant
Spoon
A type of cutlery.
Forest
1
Trees
2
Flowers
Trees
A tree is a perennial woody plant
With this understanding, you could then solve your problem without such trickery as follows.
Array = {
Forest = {},
Beach = {},
Home = {}
}
Array["Forest"] = {
Trees = "",
Flowers = "",
}
Array["Forest"]["Trees"] = "A tree is a perennial woody plant"
Array["Restaurant"] = {
Spoon = "A type of cutlery."
}
printtree(Array)
The output is then what you probably expected.
Restaurant
Spoon
A type of cutlery.
Beach
Home
Forest
Flowers
Trees
A tree is a perennial woody plant
With all of that in mind, the following accomplishes the same thing, but is much clearer in my humble opinion.
Array.Forest = {}
Array.Beach = {}
Array.Home = {}
Array.Forest.Trees = ""
Array.Forest.Flowers = ""
Array.Forest.Trees = "A tree is a perennial woody plant"
Array.Restaurant = {}
Array.Restaurant.Spoon = "A type of cutlery."
printtree(Array)
First, what you're making is not an array at all, but a dictionary. Try:
T = { Forest = { } , Beach = { } , Home = { } }
T.Forest.Spoon = "A type of cutlery"
Otherwise table.insert may be what you want in array_push
This is almost identically there in standard Lua like this:
Array.Restaurant={}
Array.Restaurant.Spoon={}
Array.Restaurant.Spoon[1]="A type of cutlery."
the table.key notation is equivalent of the table["key"] notation.
Now every item has it's description in the value corresponding to a number-key, and sub items as values corresponding to string keys.
If you really want to have exactly the same syntax as your example, you'll have to use metatables (__index and __newindex methods).