Where To Look

Create an array

• Create a nullable array
  • with NA (i.e. null) elements in it, mostly for manual typing: @nalift.
  • without NA, typically just to lift non Nullable arrays: nalift.
• Create a multidimensional table: darr, @darr to create a DictArray. The latter if you want to convert NA into appropriate null elements when manually typing.
• Create an array with labels: larr, @larr to create a LabeledArray. The latter if you want to convert NA into appropriate null elements when manually typing.
• Create a nullable array where there are many duplications, i.e. create a pooled/enumeration array: enumeration, @enumeration

Choose/Remove elements in an array

• Choose elements using index (normal way): index notation(getindex).
• Choose/Remove based on labels in LabeledArray: extract, discard.
• Choose the underlying base of LabeledArray: peel
• Choose the underlying ordered dictionary(LDict) of DictArray: peel
• Choose field name(s) from DictArray or LabeledArray: pick
• Choose the axis or axes of LabeledArray: pickaxis
• Remove fields in DictArray/LabeledArray or keys in LDict: delete

Select/Update tables in SQL style

• Create new fields and/or aggregating by some fields after choosing some elements based on given conditions: @select, selct
• Update existing fields or append new fields and/or aggregating by some fields after choosing some elements based on given conditions: @update, update

Join tables

• left join tables: leftjoin
• inner join tables: innerjoin

Dealing with NA (null elements)

• Remove Nullable: igna
• Remove Nullable from a nullable boolean array, replacing null elements with false: ignabool

Transform arrays

• Changing an array of arrays into an array, expanding the elements of array type along some direction: ungroup
• Make the fields to the last axis in LabeledArray: flds2axis
• Make the last axis to fieldsi in LabeledArray: axis2flds
• Replace the current axes along some directions with some fields LabeledArray: replace_axes
• Flatten some of the middle dimensions in an array: collapse_axes
• Reordering fields: reorder
• Renaming field names: rename
• Tensor product arrays: tensorprod
• Providing/Withdrawing field names to LabeledArray when some of its base or axes are not DictArray: providenames, withdrawnames

Map arrays

• Map a function f element by element
  • if f is from non nullable value to nullable or non nullable value: mapna
  • if f is from nullable value to nullable or non nullable value: map
• Map or reduce slices of an array: mapslices, reducedim
• Map values into another values keeping keys or field names the same: mapvalues

Calculate statistics

• Available statistical functions: msum, mprod, mmean, mmedian, mminimum, mmaximum, mmiddle, mquantile

• Summarize fields in DictArray: describe

• Fill NAs forward or backward: nafill

• Shift arrays by some amount. Can be used, for example, to obtain previous or next month time series: shift

Work with DataFrames

• convert to DataFrames: convert(::DataFrame, ::DictArray), convert(::DataFrame, ::LabeledArray)
• convert from DataFrames: convert(::DictArray, ::DataFrame), convert(::LabeledArray, ::DataFrame), convert(::EnumerationArray, ::DataFrame)

Miscellaneous

• List all field names in a DictArray: keys
• Remove all NA elements in an array, possibly reducing its size when some elements along some slice are all NA: dropna
• Combining two arrays of the same shape. The second one updates the first one only when the element is not NA: namerge
• Want to avoid excessive numbers of parentheses when applying several functions: @rap.
• Create a labels => base value nested dictionary from LabeledArray: dcube.create_dict
• Set elements in an array to NA: dcube.setna!
• Choose whether to display fields along row or column: alongrow=true/false option in show for DictArray and show for LabeledArray.
• Take some number of elements repeatedly along some direction in an array: dcube.gtake.
• Drop some number of elements along some direction in an array: dcube.gdrop.
• Set show size when printing DictArray and LabeledArray to console: dcube.set_showalongrow!!,dcube.set_showheight!!, dcube.set_showwidth!!, dcube.set_default_showsize!!
• Set display size for html output of DictArray and LabeledArray: dcube.set_dispalongrow!!, dcube.set_dispheight!!, dcube.set_dispwidth!!, dcube.set_default_dispsize!!