API Reference

Table(name1 = array1, ...)

Create a column-storage-based Table with column names name1, etc, from arrays array1, etc. The input arrays array1, etc, must share the same dimensionality and indices.

Table itself is an AbstractArray whose elements are NamedTuples of the form (name1 = first(array1), ...), etc. Rows of the table are obtained via standard array indexing table[i], and columns via table.name.

Table differs from FlexTable in that the columns are immutable - you may add, remove, rename and replace entire columns of a FlexTable, but not a Table. However, Table can access and iterate rows in local scope with fast, fully type-inferred code while FlexTable will be more efficient with a higher-order interface.

FlexTable(name1 = array1, ...)

Create a column-storage-based FlexTable with column names name1, etc, from arrays array1, etc. The input arrays array1, etc, must share the same dimensionality and indices.

FlexTable itself is an AbstractArray whose elements are NamedTuples of the form (name1 = first(array1), ...), etc. Rows of the table are obtained via standard array indexing table[i], and columns via table.name.

FlexTable differs from Table in that the columns are mutable - you may add, remove, rename and replace entire columns of a FlexTable, but not a Table. However, Table can access and iterate rows in local scope with fast, fully type-inferred code while FlexTable will be more efficient with a higher-order interface.

columns(table::Table)

Convert a Table into a NamedTuple of its columns.

columns(dataframe::FlexTable)

Convert a FlexTable into a NamedTuple of its columns.

columnnames(table)

Return a tuple of the column names of a Table.

columnnames(table)

Return a tuple of the column names of a Table.

getproperties(object, names::Tuple{Vararg{Symbol}})

Extract a set of properties with the given names from an object, returning a new object with just those properties.

Example

Extract properties a and c from a NamedTuple.

julia> nt = (a = 1, b = 2.0, c = false)
(a = 1, b = 2.0, c = false)

julia> getproperties(nt, (:a, :c))
(a = 1, c = false)

getproperties(names::Tuple{Vararg{Symbol}})

Return a function that extracts a set of properties with the given names from an object, returning a new object with just those properties.

Internally, the names are stored as a type parameter of a GetProperties object for the purpose of constant propagation. You may overload the propertytype function to control the type of the object that is returned, which by default will be a NamedTuple. See also getproperty.

Example

Extract properties a and c from a NamedTuple.

julia> nt = (a = 1, b = 2.0, c = false)
(a = 1, b = 2.0, c = false)

julia> getproperties((:a, :c))(nt)
(a = 1, c = false)

deleteproperty(object, name::Symbol)

Return a copy of object with the property with the given name removed.

Example

julia> nt = (a = 1, b = 2.0, c = false)
(a = 1, b = 2.0, c = false)

julia> deleteproperty(nt, :b)
(a = 1, c = false)

deleteproperties(object, names::Tuple{Vararg{Symbol}})

Return a copy of object with the property with the given names removed.

Example

julia> nt = (a = 1, b = 2.0, c = false, d = "abc")
(a = 1, b = 2.0, c = false)

julia> deleteproperties(nt, (:b, :d))
(a = 1, c = false)

@Compute(...)

The @Compute macro returns a function which performs a calculation on the properties of an object, such as a NamedTuple.

The input expression is standard Julia code, with $ prepended to property names. For example. if you want to refer to a property named a then use $a in the expression.

Example

julia> nt = (a = 1, b = 2.0, c = false)
(a = 1, b = 2.0, c = false)

julia> @Compute($a + $b)(nt)
3.0

@Select(...)

The @Select macro returns a function which performs an arbitrary transformation of the properties of an object, such as a NamedTuple.

The input expression is a comma-seperated list of lhs = rhs pairs. The lhs is the name of the new property to calculate. The rhs is standard Julia code, with` prepended to input property names. For example. if you want to rename an input property `ato be calledb, use@Select(b = a)`.

As a special case, if a property is to be simply replicated the = rhs part can be dropped, for example @Select(a) is synomous with @Select(a = $a).

Example

julia> nt = (a = 1, b = 2.0, c = false)
(a = 1, b = 2.0, c = false)

julia> @Select(a, sum_a_b = $a + $b)(nt)
(a = 1, sum_a_b = 3.0)