I have an Array variable. I can use the Rank property to get the number of dimensions and I know that you can use a foreach to visit each element as if the array was flattened. However, I wish to modify elements and change element references. I cannot dynamically create the correct number of for loops and I cannot invalidate an enumerator.
EDIT
Thanks for the comments, sorry about the previous lack of clarity at the end of a long tiring day. The problem:
private void SetMultiDimensionalArray(Array array)
{
for (int dimension = 0; dimension < array.Rank; dimension++)
{
var len = array.GetLength(dimension);
for (int k = 0; k < len; k++)
{
//TODO: do something to get/set values
}
}
}
Array array = new string[4, 5, 6];
SetMultiDimensionalArray(array);
Array array = new string[2, 3];
SetMultiDimensionalArray(array);
I had another look before reading this page and it appears all I need to do is create a list of integer arrays and use the overloads of GetValue and SetValue -
Array.GetValue(params int[] indices)
Array.SetValue(object value, params int[] indices)
Everything seems clear now unless someone can suggest a superior method. svick has linked to this so I will accept this answer barring any further suggestions.
It's hard to tell what exactly do you need, because your question is quite unclear.
But if you have a multidimensional array (not jagged array) whose rank you know only at runtime, you can use GetValue() to get the value at specified indices (given as an array of ints) and SetValue() to set it.
Related
I am taking a class in c# programming and cannot figure out how to do the following. I have spent hours researching and nobody else seems to have the same issues.
The question is:
Write a function named, evenOrOdd, that will accept three parameters. The first parameter is the integer array used in the above function. The second parameter is the string array from step 2 and the third parameter is an integer indicating the size of the two arrays. This function will perform the following tasks:
This function will loop through the first array, checking each value to see if it is even or odd.
For each item in the integer array, the function will then place the appropriate value, “even” or “odd”, in the corresponding position of the string array.
Hint: Using the modulus operator, (also called the modulo), to divide the number by 2 will result in either a remainder of 0 or 1. A remainder of 0 indicates an even number and a remainder of 1 indicates an odd number. The modulus operator for all of the languages in this class is %.
After calling both functions, print the maximum number determined by findMax as well as the array index position of the largest number. Next, the program will loop through the two arrays and print the integer from integer array followed by the corresponding “even” or “odd” value from the string array
I do not understand how to populate the second string array with "even" or "odd".
The two arrays should be something like this:
array1 [1,2,3,4,5,6,7,8,9,10]
then run through a loop to determine if the values are even or odd and then assign the values to the second array so it is something like this:
array2 [odd,even,odd,even,odd,even,odd,even,odd,even]
I am confused how I "link" these two arrays together so that it know index of array 1=index of array 2.
You don't have to "link" the arrays together. You can use a variable which contains the current index and use it for both arrays. Like this:
for (int i = 0; i < array1.Length; i++){
//array1[i]...
//array2[i] = ...
}
This way, you can check if the number at index i in array 1 is even or odd and then modify the index i of array 2 accordingly.
Instead of array1.Length, you can also use the third argument of the method.
It looks like a code challenge. I highly recommend you find your own way to understand and solve this kind of problem and the fundamental concepts behind it as well.
One way to code the EvenOrOdd method:
public void EvenOrOdd(int[] numbers,
string[] natures, int size)
{
for(int i=0; i < size; i++)
if(numbers[i] % 2 == 0)
natures[i] = "even";
else
natures[i] = "odd";
}
One wat to code FindMax Function:
public static (int MaxValue, int MaxIndex) FindMax(int[] numbers)
{
int major = int.MinValue;
int majorIndex = -1;
for(int i=0; i < numbers.Length; i++)
if(numbers[i] > major)
{
major = numbers[i];
majorIndex = i;
}
return (major, majorIndex);
}
Check it in dotnetFiddle
The original problem is that I am reading big chunks of binary data from a tool that is being developed.
My goal is to read data and parse it to a human readable text such as a .csv file, so I have to flatten
that data.
The data is in form of samples of a multidimensional array of floats, longs or ints or whatever. And
because the tool is under development the size and dimensions of the array may differ from an hour to hour!
(e.g. right now I may have samples of a 2*2 matrix, two hours from now they may change the data struct to
1*4, or an array of 16*12*128,...)
One part of the problem is to generate the header line of the .CSV file. I need a method that can
generate an array of strings like this:
for a 2*2: data_0_0, data_0_1, data_1_0, data_1_1, and
for a 1*4: data_0, data_1, data_2, data_3,
for a 3*4*2: data_0_0_0, data_0_0_1, data_0_0_2,...., data_2_3_0, data_2_3_1,
and so on ...
The only information that I can get from the tool each time is the dimensions and size of the array.
The tool may tell me {1}, which means a single value, {12} means an array with a length of 12, {3,4,5}
means a " 3x4x5 " element array and so on and so forth... Therefore, I need to be able to flatten any array
of a*b*c*..*x. (which should not be too hard as I can have a single for loop.
So, I'd like to create a method that generates a vector of strings (in above format) from ANY multidimensional array.
Therefore I think at the end, the header generating method will lookalike something this
public string[] GenerateNames(string dataBlockName, int[] dimensions)
{
}
One simple solution is to have lets say 10 For-loops and hope that the raw data will never have an array that has more than 10 dimensions. However, I'm looking for a better, cleaner, nicer solution!
There are a lot of questions asking how to change a vector into multidimensional arrays. My goal is the exact opposite thing and a header line with unlimited flexibility!
Thanks a lot in advance fellas!
--
Someone below suggested to use "Depth First Traversal" which I am going to look into now. Initial googling seemed promising.
You can flatten any array by merely iterating it in a foreach loop, adding each item to a list, and then converting that list back to an array.
public T[] Flatten<T>(Array array)
{
var list = new List<T>();
foreach (T item in array)
{
list.Add(item);
}
return list.ToArray();
}
where array is a rectangular array of any shape.
You don't need the array with the size, as you can check the dimensions by using the Rank property of the Array class, and the corresponding methods for obtaining the values. With this in mind and the good old .net 1.0 Array class you can write a method like this one:
public T[] Flatten<T>(Array source)
{
var arrayIndex = new int[source.Rank];
var result = new T[Enumerable.Range(0, source.Rank).Sum(i => source.GetUpperBound(i))];
var index = 0;
for(var i = 0; i < source.Rank; i++)
{
for(var j = 0; j < source.GetUpperBound(i); j++)
{
arrayIndex[i] = j;
result[index++] = (T)source.GetValue(arrayIndex);
}
}
return result;
}
It's more convoluted than a foreach, but it will provide greater flexibility on how you could traverse the original array (which is dependent on the .net implementation). As Array is not a generic class you will need to provide the element type on the method, so that for an array of integers you can call it as:
Flatten<int>(myArray);
Buffer.BlockCopy is handy here.
Note: there are some special cases to deal with so take this as pseudocode.
public T[] Flatten<T>(Array source)
{
int byteCount = Buffer.ByteLength(source);
int sizeofT = Buffer.ByteLength(new T[1]);
T[] dest = new T[(byteCount + sizeofT - 1) / sizeofT];
Buffer.BlockCopy(source,0,dest,0,byteCount);
return dest;
}
hello i will much apreciate any help.
ok let's see, first i have declare a jagged array like this and the next code
int n=1, m=3,p=0;
int[][] jag_array =new[n];
now my jagged array will have 1 array inside, next y have to fill the array like this:
car=2;
do
{
jag_array[p]= new double[car];
for (int t = 0; t < carac; t++)
{
jag_array[p][t] = variableX;
}
p=p+1
}
while(p==0)
now my jagged array looks like this(also insert some data for this example):
jag_array[0][0]=4
jag_array[0][1]=2
now my question how can i insert a new array whit out losing my previos data if i declare
jag_array[p+1]= new double[car];
i will lose the data from the previos one, i will like to look something likes this:
jag_array[0][0]=4
jag_array[0][1]=2
jag_array[1][0]=5
jag_array[1][1]=6
the reason i did not declare from the begining 2 array is beacuse i dont know how many i am going to use it could be just 1 or 20 and every time i have to create a new array whit out losing the previous data that has been already fill, thaks all for the attention,
The size of an array, once created, is by definition invariable. If you need a variable number of elements, use a List<T> - in your case, probably a List<int[]>.
The only alternative solution would be to created a new array with the new size (and assign that to your jag_array variable) and copy all the previous elements from your old array into the new array. That is unnecessarily complicated code when you can just use List<T>, but if you cannot use List<T> for any reason, here is an example:
// increase the length of jag_array by one
var old_jag_array = jag_array; // store a reference to the smaller array
jag_array = new int[old_jag_array.Length + 1][]; // create the new, larger array
for (int i = 0; i < old_jag_array.Length; i++) {
jag_array[i] = old_jag_array[i]; // copy the existing elements into the new array
}
jag_array[jag_array.Length - 1] = ... // insert new value here
I have an array of ints. They start out with 0, then they get filled with some values. Then I want to set all the values back to 0 so that I can use it again, or else just delete the whole array so that I can redeclare it and start with an array of all 0s.
You can call Array.Clear:
int[] x = new int[10];
for (int i = 0; i < 10; i++)
{
x[i] = 5;
}
Array.Clear(x, 0, x.Length);
Alternatively, depending on the situation, you may find it clearer to just create a new array instead. In particular, you then don't need to worry about whether some other code still has a reference to the array and expects the old values to be there.
I can't recall ever calling Array.Clear in my own code - it's just not something I've needed.
(Of course, if you're about to replace all the values anyway, you can do that without clearing the array first.)
I'm searching the way(s) to fill an array with numbers from 0 to a random. For example, from 0 to 12 or 1999, etc.
Of course, there is a for-loop:
var arr = int[n];
for(int i = 0; i < n; i++)
{
arr[i] = i;
}
And I can make this method been an extension for Array class. But is there some more interesting ways?
This already exists(returns IEnumerable, but that is easy enough to change if you need):
arr = Enumerable.Range(0, n);
The most interesting way in my mind produces not an array, but an IEnumerable<int> that enumerates the same number - it has the benefit of O(1) setup time since it defers the actual loop's execution:
public IEnumerable<int> GetNumbers(int max) {
for (int i = 0; i < max; i++)
yield return i;
}
This loop goes through all numbers from 0 to max-1, returning them one at a time - but it only goes through the loop when you actually need it.
You can also use this as GetNumbers(max).ToArray() to get a 'normal' array.
The best answer depends on why you need the array. The thing is, the value of any array element is equal to the index, so accessing any element is essentially a redundant operation. Why not use a class with an indexer, that just returnes the value of the index? It would be indistinguishable from a real array and would scale to any size, except it would take no memory and no time to set up. But I get the feeling it's not speed and compactness you are after. Maybe if you expand on the problem, then a better solution will be more obvious.