mastiSoft
asked on
Fast way to shift data to left
Hi.
I urgently need help.
How can I shift arrays elements to left ( not using Array.Copy)
Example:
Array.Copy and System.Buffer.BlockCopy working fine on PC and laptops but not on tablets.
Just in case you try to convince me how good Array.Copy and System.Buffer.BlockCopy I tell that they are not fast enough for me using app. on tablet.
I urgently need help.
How can I shift arrays elements to left ( not using Array.Copy)
Example:
System.Buffer.BlockCopy(pixels1d, Globals.stride, pixels1d, 0, pixels1d.Length - Globals.stride);Array.Copy and System.Buffer.BlockCopy working fine on PC and laptops but not on tablets.
Just in case you try to convince me how good Array.Copy and System.Buffer.BlockCopy I tell that they are not fast enough for me using app. on tablet.
AndyAinscow
x.RemoveAt(0) where x is your array should do the same.
hmm, what use-case? What about using a ring buffer instead of an array?
ASKER
To Andy: Please check error information in attached file.
To : ste5an. Will be buffer manipulation faster then arrays. If I use buffer how do I shift data?
2019-05-21-04_44_13-GAS---Microsoft-.png
To : ste5an. Will be buffer manipulation faster then arrays. If I use buffer how do I shift data?
2019-05-21-04_44_13-GAS---Microsoft-.png
OK. That means you are not using a collection. Have you considered using an ArrayList (or even just a List) to handle the data.
https://docs.microsoft.com/en-us/dotnet/api/system.collections.arraylist?view=netframework-4.8
A possible alternative could be to use a mix of unmanaged and managed code so you could use pointers.
https://docs.microsoft.com/en-us/dotnet/api/system.collections.arraylist?view=netframework-4.8
A possible alternative could be to use a mix of unmanaged and managed code so you could use pointers.
ASKER
How do I shift an block of data from ArrayList?
I mean first block of bytes have to disappear, all data moving to the left and at the end I'll have free bytes to save a new data there.
As I know I can remove from list element with some index or matching some value. Can I remove entire block of data with some size from ArrayList? Use for next will slow down the process. This process happens at least 300 times in second and block can have different size (up to 32767).
I mean first block of bytes have to disappear, all data moving to the left and at the end I'll have free bytes to save a new data there.
As I know I can remove from list element with some index or matching some value. Can I remove entire block of data with some size from ArrayList? Use for next will slow down the process. This process happens at least 300 times in second and block can have different size (up to 32767).
ArrayList.RemoveRange will remove a block of data.
https://docs.microsoft.com/en-us/dotnet/api/system.collections.arraylist.removerange?view=netframework-4.8
You would then have to add the new data to the ArrayList.
The removal should be very rapid, especially compared to copy or move operations. The removal just reassigns a 'pointer' to where the array starts, very little other work in memory is performed at that point wheras copy obviously performs a lot of work. The move I don't know.
The downside is the addition to the ArrayList will involve some extra work. The big question is just which is worst, you would probably have to test it under your real conditions (but I suspect the RemoveRange and Add actions will be less work especially with large numbers of items - up to 32767).
https://docs.microsoft.com/en-us/dotnet/api/system.collections.arraylist.removerange?view=netframework-4.8
You would then have to add the new data to the ArrayList.
The removal should be very rapid, especially compared to copy or move operations. The removal just reassigns a 'pointer' to where the array starts, very little other work in memory is performed at that point wheras copy obviously performs a lot of work. The move I don't know.
The downside is the addition to the ArrayList will involve some extra work. The big question is just which is worst, you would probably have to test it under your real conditions (but I suspect the RemoveRange and Add actions will be less work especially with large numbers of items - up to 32767).
ASKER
Hi Andy.
this all is amazing with list array, but I need this manipulation to create a writeable bitmap at the end.
bitmap.WritePixels() accept byte array not byte list and when I call
with list gone. It is actually working worse then with array.
This is a good idea to work with list with big data blocks but unfortunately not for my application.
this all is amazing with list array, but I need this manipulation to create a writeable bitmap at the end.
bitmap.WritePixels() accept byte array not byte list and when I call
image= pixels1d.ToArray();with list gone. It is actually working worse then with array.
for (int i1 = 0; i1 < samples; i1++)
{
//get value from data
if (val > 255) val = 255;
if (val < 0) val = 0;
Color c = colors[val];
int ii = indexPP + 3 * i1;
pixels1d.Insert(ii, c.R);
ii = ii + 1;
pixels1d.Insert(ii, c.G);
ii = ii + 1;
pixels1d.Insert(ii, c.B);
}image= pixels1d.ToArray()
Globals.bitmap.WritePixels(new Int32Rect(0, 0,samples, traces), image, Globals.stride, 0);This is a good idea to work with list with big data blocks but unfortunately not for my application.
That's why I asked "hmm, what use-case?" in the first place..
Maybe you should start describing what you're trying to achieve (top-down).
Maybe you should start describing what you're trying to achieve (top-down).
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