I have a small problem. I created a large array.
It looks like this:
var Array = [
["text10", "text11", ["text01", "text02"]],
["text20", "text21", ["text11", "text12"]]
]
If we write this way: Array[0] that shows all the elements.
If we write this way: Array[0][0] that shows "text1".
If we write this way: Array[0][2] that shows
-2 elements
-- 0: "text01"
-- 1: "text02"
.
If we write this way: Array[0][2].count or Array[0][2][0] it will not work
How do I choose each item, I need these elements for the tableView
The problem basically is that your inner array is illegal. Swift arrays must consist of elements of a single type. You have two types of element, String and Array Of String. Swift tries to compensate but the result is that double indexing can’t work, not least because there is no way to know whether a particular element will have a String or an Array in it.
The solution is to rearchitect completely. If your array entries all consist of the same pattern String plus String plus Array of String, then the pattern tells you what to do; that should be a custom struct, not an array at all.
as #matt already answered but I want to add this thing
Why Array[0][2].count or Array[0][2][0] not work
If you Define array
var array = [
["text10", "text11", ["text01", "text02"]],
["text20", "text21", ["text11", "text12"]]
]
And when you type array you can see it's type is [[Any]] However it contains String as well as Array
So When you try to get Array[0][2] Swift does not know that your array at position 2 has another array which can have count
EDIT
What you are asking now is Array of dictionary I suggest you to go with model i.e create struct or class and use it instead of dictionary
Now If you want to create dictionary then
var arrOfDict = ["text10" : ["text01", "text02"] , "text11" : ["text11", "text12"]]
And you can access with key name let arrayatZero = arrOfDict["text10"] as? [String]
Related
I have an Array lets say myarray ={1,2,3,4,5,6}
What I'm trying to do:
is generate as many as new arrays by changing each value with a value of the same array
example: myarray[0]=myarray[1] so first array will be {2,2,3,4,5,6}
then myarray[0]=myarray[2] so 2nd array will be {3,2,3,4,5,6}
later myarray[1] = myarray[0] so array will be {1,1,3,4,5,6}
and so on
I tried to think of many solutions but none of them work.
Basically, I’m given a list of strings such as:
["structA.structB.myArr[6].myVar",
"structB.myArr1[4].myArr2[2].myVar",
"structC.myArr1[3][4].myVar",
"structA.myArr1[4]",
"structA.myVar"]
These strings are describing variables/arrays from multiple structs. The integers in the arrays describe the size each array. Given a string has a/multiple arrays (1d or 2d), I want to generate a list of strings which go through each index combination in the array for that string. I thought of using for loops but issue is I don’t know how many arrays are in a given string before running the script. So I couldn’t do something like
for i in range (0, idx1):
for j in range (0, idx2):
for k in range (0, idx3):
arr.append(“structA.myArr1[%i][%i].myArr[%i]” %(idx1,idx2,idx3))
but the issue is that I don’t know how I can create multiple/dynamic for loops based on how many indexes and how I could create a dynamic append statement that changes per each string from the original list since each string will have a different number of indexes and the arrays will be in different locations of the string.
I was able to write a regex to find all the index for each string in my list of strings:
indexArr = re.findall('\[(.*?)\]', myString)
//after looping, indexArr = [['6'],['4','2'],['3','4'],['4']]
however I'm really stuck on how to achieve the "dynamic for loops" or use recursion for this. I want to get my ending list of strings to look like:
[
["structA.structB.myArr[0].myVar",
"structA.structB.myArr[1].myVar",
...
"structA.structB.myArr[5].myVar”],
[“structB.myArr1[0].myArr2[0].myVar",
"structB.myArr1[0].myArr2[1].myVar",
"structB.myArr1[1].myArr2[0].myVar",
…
"structB.myArr1[3].myArr2[1].myVar”],
[“structC.myArr1[0][0].myVar",
"structC.myArr1[0][1].myVar",
…
"structC.myArr1[2][3].myVar”],
[“structA.myArr1[0]”,
…
"structA.myArr1[3]”],
[“structA.myVar”] //this will only contain 1 string since there were no arrays
]
I am really stuck on this, any help is appreciated. Thank you so much.
The key is to use itertools.product to generate all possible combinations of a set of ranges and substitute them as array indices of an appropriately constructed string template.
import itertools
import re
def expand(code):
p = re.compile('\[(.*?)\]')
ranges = [range(int(s)) for s in p.findall(code)]
template = p.sub("[{}]", code)
result = [template.format(*s) for s in itertools.product(*ranges)]
return result
The result of expand("structA.structB.myArr[6].myVar") is
['structA.structB.myArr[0].myVar',
'structA.structB.myArr[1].myVar',
'structA.structB.myArr[2].myVar',
'structA.structB.myArr[3].myVar',
'structA.structB.myArr[4].myVar',
'structA.structB.myArr[5].myVar']
and expand("structB.myArr1[4].myArr2[2].myVar") is
['structB.myArr1[0].myArr2[0].myVar',
'structB.myArr1[0].myArr2[1].myVar',
'structB.myArr1[1].myArr2[0].myVar',
'structB.myArr1[1].myArr2[1].myVar',
'structB.myArr1[2].myArr2[0].myVar',
'structB.myArr1[2].myArr2[1].myVar',
'structB.myArr1[3].myArr2[0].myVar',
'structB.myArr1[3].myArr2[1].myVar']
and the corner case expand("structA.myVar") naturally works to produce
['structA.myVar']
I am using an array of objects in my program, and each object has several attributes. I want to be able to extract separate arrays from this array of objects, one array for each attribute.
here is a snippet of the relevant code:
dailyDataMatrix(m,n)=dailyData('',''); %creates an mxn array of dailyData objects
for i=1:m
for j=1:n
dailyDataMatrix(i,j)=dailyData(datainput1, datainput2)%dailyData constructor, sets attributes
end
end
dailyDataMatrix.attribute
But when I try to access a certain attribute as in the code above, say of type string, I get a strange result. Instead of getting an array of strings, I get something else. When I try to print it, rather than printing an array, it prints a series of individual values
ans = 'string1'
ans = 'string2'
...
When I try to call
size(dailyDataMatrix.attribute)
className = class(dailyDataMatrix.attribute)
I get
"error using size: too many input arguments" and
"error using class: The CLASS function must be called from a class constructor."
However, when I write this as
thing=dailyDataMatrix.attribute
className = class(thing)
size(thing)
I get the response
classname = 'double' and size = 1x1.
Why is this not returning an array the same size as dailyDataMatrix? And an aside question is why the two different ways of writing the code above give different results? and how can I get the result that I want?
Thanks,
Paul
You can capture all the outputs using a cell array or using square brackets if the types are same. For regular array when all values are of same type use,
thing=[dailyDataMatrix.attribute];
If the types are different you can use
thing = cell(1,N); % N is the number of elements in dailyDataMatrix
[thing{:}] = dailyDataMatrix.attribute;
So, what I am trying to do is create a variable that holds 50 lists/arrays. Accessing an element in this variable would return one of the lists. If there are no elements at a given index, I would like it to return [].
My logic to initialize this would be something like:
spectrum_map=[];
for n=1:spectrum_blocks
spectrum_map=[spectrum_map,[]];
end
However, after doing so, I simply get an empty matrix:
spectrum_map =
[]
What I want to see is something like:
spectrum_map =
[] [] [] [] [] ....
That way, if I were to access spectrum_map(2), I would see that it is empty. However, instead I would get an error that the index exceeds matrix dimensions.
Is there some other way to do what I am trying to achieve?
You can get the effect you're looking for if you use a cell array instead of a matrix.
spectrum_map = cell( 1, 50 );
spectrum_map{50}
ans =
[]
If you need to convert back to a matrix later (to perform some math on it, for instance) you can use the cell2mat function.
I am currently trying to figure out how to design some sort of loop to insert data into an array sequentially. I'm using Javascript in the Unity3D engine.
Basically, I want to store a bunch of coordinate locations in an array. Whenever the user clicks the screen, my script will grab the coordinate location. The problem is, I'm unsure about how to insert this into an array.
How would I check the array's index to make sure if array[0] is taken, then use array[1]? Maybe some sort of For loop or counter?
Thanks
To just add onto the end of an array, just use .push().
var myArray = [];
var coord1 = [12,59];
var coord2 = [87,23];
myArray.push(coord1);
myArray.push(coord2);
myArray, now contains two items (each which is an array of two coordinates).
Now, you wouldn't do it this way if you were just statically declaring everything as I've done here (you could just statically declare the whole array), but I just whipped up this sample to show you how push works to add an item onto the end of an array.
See https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/push for some reference doc on push.
In case you need to know the array's length when reading the array in the future, you can use the .length attribute.
var lengthOfArray = myArray.length;
Using the .push() method as suggested by jfriend00 is my recommendation too, but to answer your question about how to work out what the next index is you can use the array's length property. Because JavaScript arrays are zero-based The length property will return an integer one higher than the current highest index, so length will also be the index value to use if you want to add another item at the end:
anArray[anArray.length] = someValue; // add to end of array
To get the last element in the array you of course say anArray[anArray.length-1].
Note that for most purposes length will give the number of elements in the array, but I said "one higher than the current highest index" above because JavaScript arrays are quite happy for you to skip indexes:
var myArray = [];
myArray[0] = "something";
myArray[1] = "something else";
myArray[50] = "something else again";
alert(myArray.length); // gives '51'
// accessing any unused indexes will return undefined