Computation with Structured Datasets

The symbolic character of the Wolfram Language allows it to support an unprecedentedly flexible and general approach to structured datasets. Unifying both relational (SQL-like) and hierarchical (no-SQL) approaches, the Wolfram Language incorporates a new kind of uniquely powerful data query languagewith seamless scaling from direct in-memory computation to computations backed by external files or databases.

ReferenceReference

Dataset a general hierarchical dataset containing nested lists and associations

Query represent a hierarchical query on a dataset or other expression

a list of values (List)

an association of keys and values (Association)

dataset[] apply transformations to a dataset

dataset[[]] extract parts from a dataset

Explicit Parts of Datasets

dataset[[,part,]] a numbered or named part at any level

All all parts at a given level

Span (;;) a span of parts at a given level

Keys, Values keys, values in associations

Selections and Transformations

Select parts selected to satisfy a criterion

SelectFirst  ▪  Count  ▪  Counts  ▪  CountsBy  ▪  GroupBy

Select parts selected to satisfy a criterion

Sort  ▪  SortBy  ▪  Union  ▪  DeleteDuplicates

MaximalBy, MinimalBy find extreme values

Lookup look up sets of values from associations

Missing Values

Missing represent a missing value

DeleteMissing delete missing values

MissingBehavior control computations with missing values

Relational Data

JoinAcross combine tables by column

Merge combine associations by key

Custom Query Construction

Function  ▪  Query

Data Computations

Total  ▪  Mean  ▪  Median  ▪  Min  ▪  Max  ▪  ...

Basic Structural Operations

Insert  ▪  Delete  ▪  Append  ▪  Take  ▪  Drop  ▪  ...

Dataset Presentation

Grid  ▪  Column  ▪  Multicolumn  ▪  TabView  ▪  MenuView

Creating Associations

Association turn a list of rules into an association

AssociationMap create an association by applying a function to a list of keys

AssociationThread create an association from a list of keys and a list of values

Counts, CountsBy associate values with the number of times they occur

GroupBy group values by collecting those sharing a criterion

PositionIndex build an index of positions at which values occur

Creating Datasets

SemanticImport import a file as a Dataset

EntityValue obtain data from the Wolfram Knowledgebase in the form of a Dataset