Making A 2D Line Graph From An Array - Brand New at this

[m0ng00se]

Hi, I'm brand spanking-new to computers basically and have no idea what I'm doing.

I'm doing a math project where I ran a loop to count the prime numbers and then divide the number of primes by whatever number I'm at to get the current percentage of primes. I have the two values set to come out as Array1 and Array2 (p and j in my loop).

Now I want to create a graphical representation of this data set with a 2d line graph but the graph tool is really confusing.

I managed to do all of this:

Dim Array1() As Long
Dim Array2() As Decimal

For p = 1 To UpperBound

l = p / 2
IsPrime = True
For i = 1 To Math.Sqrt(l)
If p Mod 2 = 0 Or p = 1 Or p Mod ((2 * i) + 1) = 0 Then
IsPrime = False
Exit For
End If
Next

If IsPrime = True Or p = 2 Then
k += 1
Else
k = k
End If

If p = 1 Then
j = 0
Else
j = k / p
End If

ReDim Preserve Array1(p)
Array1(p) = p
ReDim Preserve Array2(p)
Array2(p) = j



I took out all the Dim parts for space, but I have no idea how to turn this into a graph. Any help would be massively appreciated, thanks.

[wakawaka]

I'm not up and up on all the graphing technologies, but there are several methods.

A) You can make your own. Not recommend for you obviously unless you want to try making controls.
B) Use the built in chart control. Documentation here
C) Use a third-party control. You would have to refer to their documentation on how to use it.

That being said, have you tried anything at all for graphing or did you just not know where to start?

[dunfiddlin]

Well first your prime test includes 1 which isn't a prime and excludes 2 and 3 which are. But what exactly are you graphing? Your arrays have only one significant value no matter how large they are. It's not at all clear why you need an array at all, in fact. Your stated aim of graphing % of numbers that are prime by number reached makes very little sense not least because values will swing wildly.

1 > 0
2 > 50
3 > 66
4 > 50
5 > 60
6 > 50
7 > 57

[SJWhiteley]

1. Create an array of drawing.pointF() structures;
2. Parse your coordinate arrays into the .X and .Y properties of the PointF structures;
2a. Scale the X and Y values for the pixel region you want to plot the points in (note that the origin is top left instead of bottom left);
3. Override the OnPaint() method or handle the Paint() event;
4. Draw the PointF array structure using graphics.DrawLines();
5. In the resize event, rescale the PointF array as appropriate, and Invalidate the drawing region.