Merge pull request #141 from piever/specialdocs

add docs for special selectors (and export them)

Author: shashi

docs/src/api/index.md

@@ -38,6 +38,13 @@ Derivatives of [`select`](@ref) that are convenient for modifying a table's colu
 - [`insertcolbefore`](@ref) - insert a column before another
 - [`renamecol`](@ref) - rename a column
 
+Special selectors to select a subset of columns.
+
+- [`All`](@ref) - select all columns
+- [`Not`](@ref) - select complementary
+- [`Keys`](@ref) - select primary columns
+- [`Between`](@ref) - select columns between two extremes
+
 ## [Aggregation](@ref)
 
 Grouping and reduction with functions or Online statistics.

docs/src/api/selection.md

@@ -85,3 +85,41 @@ insertcolbefore
 ```@docs
 renamecol
 ```
+
+## Column special selection
+
+This section describes some special types that can be used to simplify column selection. These types can be used in combination with `select`, `rows` or `columns`, as well as any other function that requires a `by` or `select` argument.
+
+```@docs
+All
+```
+
+```@docs
+Not
+```
+
+```@docs
+Keys
+```
+
+```@docs
+Between
+```
+
+Finally, to select columns whose name respects a given predicate, pass a function to `select` (or `rows`, or `columns`):
+
+```jldoctest specialselector
+julia> t = table([0.01, 0.05], [2,1], [2, 3], names=[:t, :x, :z])
+Table with 2 rows, 3 columns:
+t     x  z
+──────────
+0.01  2  2
+0.05  1  3
+
+julia> select(t, i -> i != :z)
+Table with 2 rows, 2 columns:
+t     x
+───────
+0.01  2
+0.05  1
+```

src/JuliaDB.jl

@@ -15,7 +15,7 @@ export IndexedTable, NDSparse, NextTable, Columns, colnames,
        table, ndsparse, compute, groupby, summarize, groupreduce, groupjoin,
        ColDict, insertafter!, insertbefore!, @cols, setcol, pushcol,
        popcol, insertcol, insertcolafter, insertcolbefore, permutecols,
-       renamecol, NA, dropna, flatten, ML
+       renamecol, NA, dropna, flatten, ML, All, Not, Between, Keys
 
 include("util.jl")
 include("serialize.jl")