Find Attribute Array Statistics

Group (Subgroup)

DREAM3D Review (Statistics)

Description

This Filter computes a variety of statistics for a given scalar array. The currently available statistics are array length, minimum, maximum, (arithmetic) mean, median, standard deviation, and summation; any combination of these statistics may be computed by this Filter. Any scalar array, of any primitive type, may be used as input. The type of the output arrays depends on the kind of statistic computed:

Statistic Primitive Type
Length signed 64-bit integer
Minimum same type as input
Maximum same type as input
Mean double
Median double
Standard Deviation double
Summation double
Standardized double

The user may optionally use a mask to specify points to be ignored when computing the statistics; only points where the supplied mask is true will be considered when computing statistics. Additionally, the user may select to have the statistics computed per Feature or Ensemble by supplying an Ids array. For example, if the user opts to compute statistics per Feature and selects an array that has 10 unique Feature Ids, then this Filter will compute 10 sets of statistics (e.g., find the mean of the supplied array for each Feature, find the total number of points in each Feature (the length), etc.).

The input array may also be standardized, meaning that the array values will be adjusted such that they have a mean of 0 and unit variance. This Standardize Data option requires the selection of both the Find Mean and Find Standard Deviation options. The standardized data will be saved as a new array object stored in the same Attribute Matrix as the input array. Note that if the Standardize Data option is selected, the mean and standard deviation values created by this Filter reflect the mean and standard deviation of the original array; the new standardized array has a mean of 0 and unit variance. The standardized array will be computed in double precision. If the statistics are being computed per Feature or Ensemble, then the array values are standardized according to the mean and standard deviation for each Feature/Ensemble. For example, if 5 unique Features were being analyzed and Standardize Data was selected, then the array values for Feature 1 would be standardized according to the mean and standard deviation for Feature 1, then the array values for Feature 2 would be standardized according to the mean and standard deviation for Feature 2, and so on for the remaining Features.

The user must select a destination Attribute Matrix in which the computed statistics will be stored. If electing to Compute Statistics Per Feature/Ensemble, then a reasonable selection for this array is the Feature/Ensemble Attribute Matrix associated with the supplied Feature/Ensemble Ids. However, the only requirement is that the number of columns in the selected destination Attribute Matrix match the number of Features/Ensembles specified by the supplied Id array. This requirement is enforced at run time. If computing statistics for the entire input array, then only one value is computed per statistic; therefore, the arrays produced only contain one value. In this case, the destination Attribute Matrix should only contain 1 tuple. If such a Generic Attribute Matrix does not exist, it can be created.

Special operations occur for certain statistics if the supplied array is of type bool (for example, a mask array produced when thresholding). The length, minimum, maximum, median, and summation are computed as normal (although the resulting values may be platform dependent). The mean and standard deviation for a boolean array will be true if there are more instances of true in the array than false. If Standardize Data is chosen for a boolean array, no actual modifications will be made to the input. These operations for boolean inputs are chosen as a basic convention, and are not intended be representative of true boolean logic.

Parameters

Name Type Description
Find Length bool Whether to compute the length of the input array
Find Minimum bool Whether to compute the minimum of the input array
Find Maximum bool Whether to compute the maximum of the input array
Find Mean bool Whether to compute the arithmetic mean of the input array
Find Median bool Whether to compute the median of the input array
Find Standard Deviation bool Whether to compute the standard deviation of the input array
Find Summation bool Whether to compute the summation of the input array
Use Mask bool Whether to use a boolean mask array to ignore certain points flagged as false from the statistics
Compute Statistics Per Feature/Ensemble bool Whether the statistics should be computed on a Feature/Ensemble basis
Standardize Data bool Whether the input array should be standardized to have mean of 0 and unit variance; Find Mean and Find Standard Deviation must be selected to use this option

Required Geometry

None

Required Objects

Kind Default Name Type Component Dimensions Description
Any Attribute Array None Any (1) Input Attribute Array for which to compute statistics
Attribute Array None int32_t (1) Specifies to which Feature/Ensemble each point in the input Attribute Array belongs, if Compute Statistics Per Feature/Ensemble is checked
Attribute Array Mask bool (1) Specifies if the point is to be counted in the statistics, if Use Mask is checked
Destination Attribute Matrix None Any N/A Attribute Matrix in which to store the computed statistics

Created Objects

Kind Default Name Type Component Dimensions Description
Attribute Array Length int64_t (1) Length of the input array, if Find Length is checked
Attribute Array Minimum same as input Attribute Array (1) Minimum of the input array, if Find Minimum is checked
Attribute Array Maximum same as input Attribute Array (1) Maximum of the input array, if Find Maximum is checked
Attribute Array Mean double (1) Arithmetic mean of the input array, if Find Mean is checked
Attribute Array Median double (1) Median of the input array, if Find Median is checked
Attribute Array Standard Deviation double (1) Standard deviation of the input array, if Find Standard Deviation is checked
Attribute Array Summation double (1) Summation of the input array, if Find Summation is checked
Attribute Array Standardized double (1) Standardized version of the input array, if Standardize Data is checked

Example Pipelines

Please see the description file distributed with this plugin.

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