# Mapping PVector heading() to another range
**URL:** https://discourse.processing.org/t/mapping-pvector-heading-to-another-range/42999
**Category:** Coding Questions
**Created:** [October 17, 2023, 9:42pm UTC](https://discourse.processing.org/t/mapping-pvector-heading-to-another-range/42999 "2023-10-17T21:42:49Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@gomako](https://discourse.processing.org/u/gomako)
#### Post date: [October 17, 2023, 9:42pm UTC](https://discourse.processing.org/t/mapping-pvector-heading-to-another-range/42999/1 "2023-10-17T21:42:49Z")
I am creating a `PVector` using the `.fromAngle()` method. I use an variable that increments from 0 to TWO\_PI. When I access the `heading()` of the vector, I get a range from 0 → PI → -PI → 0. Is this expected behaviour? I’m trying to map the angle of the vector to another range and am struggling to find a way to do this.
Am I being stupid? Is there another way to access the angle of the vector that isn’t `.heading()`?
---
### Author:  [@glv](https://discourse.processing.org/u/glv)
#### Post date: [October 18, 2023, 10:02am UTC](https://discourse.processing.org/t/mapping-pvector-heading-to-another-range/42999/2 "2023-10-18T10:02:33Z")
Hello @gomako,
> [@gomako](#):
>
> Is this expected behaviour?
_PVector.heading()_ uses _atan2()_ under the hood:
[https://github.com/benfry/processing4/blob/main/core/src/processing/core/PVector.java#L849](https://github.com/benfry/processing4/blob/main/core/src/processing/core/PVector.java#L849)
_atan2()_ Processing reference:
> **[atan2() / Reference](https://processing.org/reference/atan2_.html)**
>
> Calculates the angle (in radians) from a specified point to the coordinate origin as measured from the positive x-axis. Values are returned as a float in the range from PI to -PI.…
_atan2()_ Wikipedia reference:
> **[atan2](https://en.wikipedia.org/wiki/Atan2)**
>
> In computing and mathematics, the function atan2 is the 2-argument arctangent. By definition,
>
>
>
> θ
> =
> atan2
>
> (
> y
> ,
> x
> )
>
>
> {\\displaystyle \\theta =\\operatorname {atan2} (y,x)}
>
> is the angle measure (in radians, with
>
>
>
> −
> π
> \<
> θ
> ≤
> π
>
>
> {\\displaystyle -\\pi \<\\theta \\leq \\pi }
>
> ) between the positive
>
>
>
> x
> ...
Angles are clockwise in Processing:
> **[2D Transformations](https://processing.org/tutorials/transform2d/)**
>
> Learn how to translate, rotate, and scale shapes using 2D transformations.
A quick demo to map values returned from _atan2()_ to 0 to TAU radians (0 to 360 degrees):
```auto
PVector v;
void setup()
{
size(500, 500);
}
void draw()
{
background(255);
translate(width/2, height/2);
v = new PVector(mouseX-width/2, mouseY-height/2);
line(0, 0, v.x, v.y);
float h = v.heading();
println(h, degrees(h));
if (h<0) h+= TAU; // This does the mapping! TAU = TWO_PI
println(h, degrees(h));
println();
String s = str(int(degrees(h)))+ "°"; // Mofify if you want decimal places
fill(255, 0, 0);
textSize(24);
text(s, v.x, v.y);
}
```
There is also a _map()_ function if you want to use that:
> **[map() / Reference](https://processing.org/reference/map_.html)**
>
> Re-maps a number from one range to another. In the first example above, the number 25 is converted from a value in the range of 0 to 100 into a value that ranges from the left edge of the w…
`:)`
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### Author:  [@gomako](https://discourse.processing.org/u/gomako)
#### Post date: [October 18, 2023, 10:19am UTC](https://discourse.processing.org/t/mapping-pvector-heading-to-another-range/42999/3 "2023-10-18T10:19:22Z")
Ah thank you so much for the detailed answer, that is just what I needed. I couldn’t quite figure out how to make the -PI to -1 bit into PI+1 to TWO\_PI and the following is what did it.
> [@glv](#):
>
> `if (h<0) h+= TAU; // This does the mapping! TAU = TWO_PI`
Thanks again for the references too, I appreciate it.