Math Is Fun Forum

Why at angle -37.7468, you got direction code 1, and i get 0.

Is that some logical reason orwhat.
I do not get it .

you are exactly Right @phrontister
Thank you for explaing well.

Yes this time,,i am interested in assigning 8 numbers to each direction based on its angle.
Previously, i had come cross with 16 direction code. but now i need to work on 8 direction code. I had already calculated and mention in my reply #6 and method of this is given in reply #5 .

but i am not satisfy with my calculated 8 direction codes.

anyone can help me to get the 8 numbers of directions based on its angle?

I think my coordinates are window screen coordinates like shown below

The image is attached again in the below fig

The x,y coordinates are as follows

@ 0 : [260,308]
@ 1 : [209,324]
@ 2 : [201,375]
@ 3 : [242,438]
@ 4 : [275,445]
@ 5 : [337,397]
@ 6 : [343,365]
@ 7 : [302,318]
@ 8 : [235,312]

... the following are the dx, dy and its angle in radian and degree//
dx , dy : -51 16

angle in radian : 2.83759

angle in degree : 162.582

dx , dy : -8 51

angle in radian : 1.72639

angle in degree : 98.9149

dx , dy : 41 63

angle in radian : 0.993863

angle in degree : 56.9442

dx , dy : 33 7

angle in radian : 0.209023

angle in degree : 11.9761

dx , dy : 62 -48

angle in radian : -0.658806

angle in degree : -37.7468

dx , dy : 6 -32

angle in radian : -1.38545

angle in degree : -79.3803

dx , dy : -41 -47

angle in radian : -2.28812

angle in degree : -131.1

dx , dy : -67 -6

angle in radian : -3.05228

angle in degree : -174.883

Next , below are the direction codes
Calculated direction Codes
4 6 7 0 0 1 2 3

Well, what i wanna is .. assign the 8 direction codes to each angle of line segment.

the 8 direction code is given below.

I have set of points which represent a shape of triangle. i wanna minimize points which best maintain the shape. In other to do that, i found one method in paper called, least angle method. I tried to google it but i could not find any useful that could help me to understand it.
I found only least angle regression which i am not sure its same or not.
Anyone could help me to lead it. thanks

Hi ,

Hope you are good.
This time i tested 8 direction codes on above given points

My direction code result is shown in the below image.

The points are
105 66
114 92
104 11
99 131
71 144
37 168

And the 8 direction codes are as follows
2
7
6
6

My method of calculating the direction code is same like you directed me for 16 direction  codes.

I used the following steps for calculating the direction Codes

1. take angle
2. divide by 40
3. add 0.5 to round up or down correctly
4. take the integer part
5. subtract from 8 to get the correct rotational direction
6. use mod 8 division to get the numbers in range.

The 8 direction code image is shown below

In the image, numbers are assigned to each direction.

=-----------------------------
But my direction  codes seems not correct.

Hi Bob, sorry i did not notice about the questions.
I think i mentioned before that i am computing angle using atan2 (dy / dx)

And i computed dy, dx as follows dx = abs (p2.x - p1.x) , dy = abs (p2.y - p1.y);

I did programming in c++.

I have this image

I have these points of the above drawn character

x: 126, y: 279
x: 172, y: 257
x: 209, y: 238
x: 247, y: 230
x: 271, y: 225
x: 249, y: 334
x: 228, y: 369
x: 193, y: 383
x: 122, y: 411
x: 64, y: 439
x: 79, y: 451
x: 128, y: 449
x: 191, y: 416
x: 240, y: 376
x: 264, y: 358
x: 279, y: 343
x: 86, y: 270
x: 110, y: 256
x: 133, y: 246
x: 169, y: 248
x: 199, y: 250
x: 197, y: 273
x: 193, y: 304
x: 182, y: 334
x: 161, y: 366
x: 146, y: 397
x: 143, y: 419
x: 146, y: 434
x: 160, y: 443
x: 185, y: 420
x: 219, y: 390
x: 247, y: 366
x: 289, y: 343
x: 327, y: 340

-----------
and these are the angles computed by atan2 in degree form

@ 0 , Angle: -25.56
@ 1 , Angle: -27.1811
@ 2 , Angle: -11.8887
@ 3 , Angle: -11.7683
@ 4 , Angle: 101.411
@ 5 , Angle: 120.964
@ 6 , Angle: 158.199
@ 7 , Angle: 158.477
@ 8 , Angle: 154.231
@ 9 , Angle: 38.6598
@ 10 , Angle: -2.33731
@ 11 , Angle: -27.646
@ 12 , Angle: -39.2257
@ 13 , Angle: -36.8699
@ 14 , Angle: -45
@ 15 , Angle: -159.281
@ 16 , Angle: -30.2564
@ 17 , Angle: -23.4986
@ 18 , Angle: 3.17983
@ 19 , Angle: 3.81407
@ 20 , Angle: 94.9697
@ 21 , Angle: 97.3524
@ 22 , Angle: 110.136
@ 23 , Angle: 123.275
@ 24 , Angle: 115.821
@ 25 , Angle: 97.7652
@ 26 , Angle: 78.6901
@ 27 , Angle: 32.7352
@ 28 , Angle: -42.6141
@ 29 , Angle: -41.4237
@ 30 , Angle: -40.6013
@ 31 , Angle: -28.706
@ 32 , Angle: -4.51399

---------------

and these are the direction codes.

@ 0 : 1
@ 1 : 1
@ 2 : 1
@ 3 : 1
@ 4 : 12
@ 5 : 12
@ 6 : 10
@ 7 : 10
@ 8 : 10
@ 9 : 15
@ 10 : 0
@ 11 : 1
@ 12 : 2
@ 13 : 2
@ 14 : 2
@ 15 : 7
@ 16 : 1
@ 17 : 1
@ 18 : 0
@ 19 : 0
@ 20 : 13
@ 21 : 13
@ 22 : 12
@ 23 : 12
@ 24 : 12
@ 25 : 13
@ 26 : 14
@ 27 : 0
@ 28 : 2
@ 29 : 2
@ 30 : 2
@ 31 : 1
@ 32 : 0

----------------

I am not satisfy with my direction numbers to each angle.

Anyone help me to check it. thanks