Ascent Expressions Documentation

Functions

avg(arg1)

Return the average of an array.

Parameters:arg1 (array) –
Return type:double
avg(arg1)

Return the field average of a mesh variable.

Parameters:arg1 (field) –
Return type:double
field_nan_count(arg1)

Return the number of NaNs in a mesh variable.

Parameters:arg1 (field) –
Return type:double
field_inf_count(arg1)

Return the number of -inf and +inf in a mesh variable.

Parameters:arg1 (field) –
Return type:double
max(arg1, arg2)

Return the maximum of two scalars.

Parameters:
  • arg1 (scalar) –
  • arg2 (scalar) –
Return type:

double
max(arg1)

Return the maximum value from the meshvar. Its position is also stored and is accessible via the position function.

Parameters:arg1 (field) –
Return type:value_position
max(arg1)

Return the maximum of an array.

Parameters:arg1 (array) –
Return type:double
min(arg1)

Return the minimum value from the meshvar. Its position is also stored and is accessible via the position function.

Parameters:arg1 (field) –
Return type:value_position
min(arg1, arg2)

Return the minimum of two scalars.

Parameters:
  • arg1 (scalar) –
  • arg2 (scalar) –
Return type:

double
min(arg1)

Return the minimum of an array.

Parameters:arg1 (array) –
Return type:double
sum(arg1)

Return the sum of a field.

Parameters:arg1 (field) –
Return type:double
sum(arg1)

Return the sum of an array.

Parameters:arg1 (array) –
Return type:double
cycle()

Return the current simulation cycle.

Return type:int
vector(arg1, arg2, arg3)

Return the 3D position vector for the input value.

Parameters:
  • arg1 (scalar) –
  • arg2 (scalar) –
  • arg3 (scalar) –
Return type:

vector
magnitude(arg1)

Return the magnitude of the input vector.

Parameters:arg1 (vector) –
Return type:double
abs(arg1)

Return the absolute value of the input.

Parameters:arg1 (scalar) –
Return type:scalar
exp(arg1)

Return the base e exponential.

Parameters:arg1 (scalar) –
Return type:double
pow(arg1, arg2)

Returns base raised to the power exponent. pow(base, exponent)

Parameters:
  • arg1 (scalar) –
  • arg2 (scalar) –
Return type:

double
log(arg1)

Returns the natural logarithm of the argument

Parameters:arg1 (scalar) –
Return type:double
histogram(arg1[, num_bins][, min_val][, max_val])

Return a histogram of the mesh variable. Return a histogram of the mesh variable.

Parameters:
  • arg1 (field) –
  • num_bins (int) – defaults to 256
  • min_val (scalar) – defaults to min(arg1)
  • max_val (scalar) – defaults to max(arg1)
Return type:

histogram
history(expr_name[, relative_index][, absolute_index])

As the simulation progresses the expressions are evaluated repeatedly. The history function allows you to get the value of previous evaluations. For example, if we want to evaluate the difference between the original state of the simulation and the current state then we can use an absolute index of 0 to compare the initial value with the current value: val - history(val, absolute_index=0). Another example is if you want to evaluate the relative change between the previous state and the current state: val - history(val, relative_index=1).

Note

Exactly one of relative_index or absolute_index must be passed. If the argument name is not specified relative_index will be used.

Parameters:
  • expr_name (anytype) – expr_name should be the name of an expression that was evaluated in the past.
  • relative_index (int) – The number of evaluations ago. This should be less than the number of past evaluations. For example, history(pressure, relative_index=1) returns the value of pressure one evaluation ago.
  • absolute_index (int) – The index in the evaluation history. This should be less than the number of past evaluations. For example, history(pressure, absolute_index=0) returns the value of pressure from the first time it was evaluated.
Return type:

anytype
entropy(hist)

Return the Shannon entropy given a histogram of the field.

Parameters:hist (histogram) –
Return type:double
pdf(hist)

Return the probability distribution function (pdf) from a histogram.

Parameters:hist (histogram) –
Return type:histogram
cdf(hist)

Return the cumulative distribution function (cdf) from a histogram.

Parameters:hist (histogram) –
Return type:histogram
bin(hist, bin)

Return the value of the bin at index bin of a histogram.

Parameters:
  • hist (histogram) –
  • bin (int) –
Return type:

double
bin(hist, val)

Return the value of the bin with axis-value val on the histogram.

Parameters:
  • hist (histogram) –
  • val (scalar) –
Return type:

double
bin(binning, index)

returns a bin from a binning by index

Parameters:
  • binning (binning) –
  • index (int) –
Return type:

bin
field(arg1)

Return a mesh field given a its name.

Parameters:arg1 (string) –
Return type:field
bounds([topology])

Returns the spatial bounds of a mesh.

Parameters:topology (string) –
Return type:aabb
point_and_axis(binning, axis, threshold, point[, miss_value][, direction])

returns the first values in a binning that exceeds a threshold from the given point.

Parameters:
  • binning (binning) –
  • axis (string) –
  • threshold (double) –
  • point (double) –
  • miss_value (scalar) –
  • direction (int) –
Return type:

bin
max_from_point(binning, axis, point)

returns the closest max value from a reference point on an axis

Parameters:
  • binning (binning) –
  • axis (string) –
  • point (double) –
Return type:

value_position
lineout(samples, start, end[, fields][, empty_val])

returns a sampled based line out

Parameters:
  • samples (int) –
  • start (vector) –
  • end (vector) –
  • fields (list) –
  • empty_val (double) –
Return type:

array
quantile(cdf, q[, interpolation])

Return the q-th quantile of the data along the axis of cdf. For example, if q is 0.5 the result is the value on the x-axis which 50 percent of the data lies below.

Parameters:
  • cdf (histogram) – CDF of a histogram.
  • q (double) – Quantile between 0 and 1 inclusive.
  • interpolation (string) –

    Specifies the interpolation method to use when the quantile lies between two data points i < j:

    • linear (default): i + (j - i) * fraction, where fraction is the fractional part of the index surrounded by i and j.
    • lower: i.
    • higher: j.
    • nearest: i or j, whichever is nearest.
    • midpoint: (i + j) / 2
Return type:

double
axis(name[, bins][, min_val][, max_val][, num_bins][, clamp])

Defines a uniform or rectilinear axis. When used for binning the bins are inclusive on the lower boundary and exclusive on the higher boundary of each bin. Either specify only bins or a subset of the min_val, max_val, num_bins options.

Parameters:
  • name (string) – The name of a scalar field on the mesh or one of 'x', 'y', or 'z'. name can also be the empty string ‘’ if reduction_op is either sum or pdf to mean we want to count the number of elements in the bin as our reduction variable.
  • bins (list) – A strictly increasing list of scalars containing the values for each tick. Used to specify a rectilinear axis.
  • min_val (scalar) – Minimum value of the axis (i.e. the value of the first tick). Defaults to min(name) for fields and for 'x', 'y', or 'z' the minimum value on the topology.
  • max_val (scalar) – Maximum value of the axis (i.e. the value of the last tick).Defaults to max(name) for fields and for 'x', 'y', or 'z' the maximum value on the topology.
  • num_bins (int) – Number of bins on the axis (i.e. the number of ticks minus 1). Defaults to 256.
  • clamp (bool) – Defaults to False. If True, values outside the axis should be put into the bins on the boundaries.
Return type:

axis
binning(reduction_var, reduction_op, bin_axes[, empty_bin_val][, component])

Returns a multidimensional data binning.

Parameters:
  • reduction_var (string) – The variable being reduced. Either the name of a scalar field on the mesh or one of 'x', 'y', or 'z'.
  • reduction_op (string) –

    The reduction operator to use when putting values in bins. Available reductions are:

    • min: minimum value in a bin
    • max: maximum value in a bin
    • sum: sum of values in a bin
    • avg: average of values in a bin
    • pdf: probability distribution function
    • std: standard deviation of values in a bin
    • var: variance of values in a bin
    • rms: root mean square of values in a bin
  • bin_axes (list) – List of Axis objects which define the bin axes.
  • empty_bin_val (scalar) – The value that empty bins should have. Defaults to 0.
  • component (string) – the component of a vector field to use for the reduction. Example ‘x’ for a field defined as ‘velocity/x’
Return type:

binning

Objects

histogram
Parameters:
  • value (array) –
  • min_val (double) –
  • max_val (double) –
  • num_bins (int) –
  • clamp (bool) –
value_position
Parameters:
  • value (double) –
  • position (vector) –
aabb
Parameters:
  • min (vector) –
  • max (vector) –
vector
Parameters:
  • x (double) –
  • y (double) –
  • z (double) –
bin
Parameters:
  • min (double) –
  • max (double) –
  • center (double) –
  • value (double) –