Random Numbers

Note

The wiggle method—which is used to randomly vary a property value—is in the Property attributes and methods category. See Property attributes and methods.


seedRandom(offset, timeless=false)

Description

The random and gaussRandom methods use a seed value that controls the sequence of numbers. By default, the seed is computed as a function of a unique layer identifier, the property within the layer, the current time, and an offset value of 0. Call seedRandom to set the offset to something other than 0 to create a different random sequence. Use true for the timeless argument to not use the current time as input to the random seed. Using true for the timeless argument allows you to generate a random number that doesn’t vary depending on the time of evaluation. The offset value, but not the timeless value, is also used to control the initial value of the wiggle function.

For example, this expression on the Opacity property sets the Opacity value to a random value that does not vary with time:

seedRandom(123456, true);
random()*100

The multiplication by 100 in this example converts the value in the range 0–1 returned by the random method into a number in the range 0–100; this range is more typically useful for the Opacity property, which has values from 0% to 100%.

Parameters

offset Number
timeless Boolean

Type

None


random()

Description

Returns a random number in the range 0–1.

Note

In After Effects CC and CS6, the behavior of random() is changed to be more random when layer IDs are close together. The wiggle() expression is not affected.

Type

Number


random(maxValOrArray)

Description

If maxValOrArray is a Number, this method returns a number in the range from 0 to maxValOrArray. If maxValOrArray is an Array, this method returns an Array with the same dimension as maxValOrArray, with each component ranging from 0 to the corresponding component of maxValOrArray.

Parameters

maxValOrArray Number or Array

Type

Number or Array


random(minValOrArray, maxValOrArray)

Description

If minValOrArray and maxValOrArray are Numbers, this method returns a number in the range from minValOrArray to maxValOrArray.

If the arguments are Arrays, this method returns an Array with the same dimension as the argument with the greater dimension, with each component in the range from the corresponding component of minValOrArray to the corresponding component of maxValOrArray.

For example, the expression random([100, 200], [300, 400]) returns an Array whose first value is in the range 100–300 and whose second value is in the range 200–400. If the dimensions of the two input Arrays don’t match, higher-dimension values of the shorter Array are filled out with zeros.

Parameters

minValOrArray Number or Array
maxValOrArray Number or Array

Type

Number or Array


gaussRandom()

Description

The results have a Gaussian (bell-shaped) distribution. Approximately 90% of the results are in the range 0–1, and the remaining 10% are outside this range.

Type

Number


gaussRandom(maxValOrArray)

Description

When maxValOrArray is a Number, this method returns a random number. Approximately 90% of the results are in the 0 to maxValOrArray range, and the remaining 10% are outside this range.

When maxValOrArray is an Array, this method returns an Array of random values, with the same dimension as maxValOrArray. 90% of the values are in the range from 0 to maxValOrArray, and the remaining 10% are outside this range.

The results have a Gaussian (bell-shaped) distribution.

Parameters

maxValOrArray Number or Array

Type

Number or Array


gaussRandom(minValOrArray, maxValOrArray)

Description

If minValOrArray and maxValOrArray are Numbers, this method returns a random number. Approximately 90% of the results are in the range from minValOrArray to maxValOrArray, and the remaining 10% are outside this range.

If the arguments are Arrays, this method returns an Array of random numbers with the same dimension as the argument with the greater dimension. For each component, approximately 90%``of the results are in the range from the corresponding component of ``minValOrArray to the corresponding component of maxValOrArray, and the remaining 10% are outside this range.

The results have a Gaussian (bell-shaped) distribution.

Parameters

minValOrArray Number or Array
maxValOrArray Number or Array

Type

Number or Array


noise(valOrArray)

Description

Returns a number in the range from -1 to 1. The noise is not actually random; it is based on Perlin noise, which means that the return values for two input values that are near one another tend to be near one another. This type of noise is useful when you want a sequence of seemingly random numbers that don’t vary wildly from one to the other—as is usually the case when animating any apparently random natural motion.

Example:

rotation + 360*noise(time)

Parameters

valOrArray Number or an Array (2- or 3-dimensional)

Type

Number