ee.Array.acos

AI-generated Key Takeaways

• Calculates the arccosine (inverse cosine) of each element in an input array.

• Returns a new array containing the arccosine values in radians.

• Accepts an array as input and operates on each element independently.

• Provides examples in JavaScript, Python, and Colab to demonstrate usage and visualization.

On an element-wise basis, computes the arccosine in radians of the input.

Usage	Returns
Array.acos()	Array

Argument	Type	Details
this: input	Array	The input array.

Examples

Code Editor (JavaScript)

print(ee.Array([-1]).acos());  // [π]
print(ee.Array([0]).acos());  // [π/2]
print(ee.Array([1]).acos());  // [0]

var start = -1;
var end = 1;
var points = ee.Array(ee.List.sequence(start, end, null, 50));
var values = points.acos();

// Plot acos() defined above.
var chart = ui.Chart.array.values(values, 0, points)
    .setOptions({
      viewWindow: {min: start, max: end},
      hAxis: {
        title: 'x',
        viewWindowMode: 'maximized',
        ticks: [
          {v: start, f: start},
          {v: 0, f: 0},
          {v: end, f: end}]
      },
      vAxis: {
        title: 'acos(x)',
        ticks: [
          {v: 0, f: 0},
          {v: Math.PI / 2, f: 'π/2'},
          {v: Math.PI, f: 'π'}]
      },
      lineWidth: 1,
      pointSize: 0,
    });
print(chart);

Python setup

See the Python Environment page for information on the Python API and using geemap for interactive development.

import ee
import geemap.core as geemap

Colab (Python)

import math
import altair as alt
import pandas as pd

display(ee.Array([-1]).acos())  # [π]
display(ee.Array([0]).acos())  # [π/2]
display(ee.Array([1]).acos())  # [0]

start = -1
end = 1
points = ee.Array(ee.List.sequence(start, end, None, 50))
values = points.acos()

df = pd.DataFrame({'x': points.getInfo(), 'acos(x)': values.getInfo()})

# Plot acos() defined above.
alt.Chart(df).mark_line().encode(
    x=alt.X('x', axis=alt.Axis(values=[start, 0, end])),
    y=alt.Y('acos(x)', axis=alt.Axis(values=[0, math.pi / 2, math.pi]))
)