The Reference command creates a reference to a Quandl data set, and retrieves some metadata about the data available for this data set.

The two calling sequences are exactly equivalent: a call to Reference in the DataSets package interprets its first argument as the name of a data source, and if it is "Quandl", it calls DataSets[Quandl][Reference].

The reference object retrieves the data only when necessary, which is when it is implicitly or explicitly converted to another type.

Retrieved data is cached so that subsequent conversions will be faster.

Reference objects can be created without specifying the Quandl identifier with DataSets[Search] or DataSets[InsertSearchBox].

Quandl reference objects are compatible with any command in the TimeSeriesAnalysis package that makes use of TimeSeries objects.

$\mathrm{with}\left(\mathrm{DataSets}\right)\:$

$\mathrm{ref}≔\mathrm{Reference}\left(''Quandl''\,''FRED/CANPOPL''\right)$

$\mathrm{ref}≔\left[\begin{array}{c}\mathrm{Data\; set}\\ \mathrm{Population\; in\; Canada\; (DISCONTINUED)}\\ \mathrm{Quandl\; FRED/CANPOPL}\\ \mathrm{up\; to\; 52\; rows\; (annual),\; 1\; column}\\ \mathrm{1960-01-01\; -\; 2011-01-01}\end{array}\right]$

$\mathrm{Quandl}:-\mathrm{Reference}\left(''FRED/CANPOPL''\right)$

$\left[\begin{array}{c}\mathrm{Data\; set}\\ \mathrm{Population\; in\; Canada\; (DISCONTINUED)}\\ \mathrm{Quandl\; FRED/CANPOPL}\\ \mathrm{up\; to\; 52\; rows\; (annual),\; 1\; column}\\ \mathrm{1960-01-01\; -\; 2011-01-01}\end{array}\right]$

$\mathrm{GetIdentifier}\left(\mathrm{ref}\right)$

$''FRED/CANPOPL''$

$\mathrm{convert}\left(\mathrm{ref}\,\'\mathrm{Matrix}\'\right)$

$\mathrm{with}\left(\mathrm{TimeSeriesAnalysis}\right)\:$

$\mathrm{TimeSeriesPlot}\left(\mathrm{ref}\right)$

$\mathrm{esm}≔\mathrm{ExponentialSmoothingModel}\left(\mathrm{ref}\right)$

$\mathrm{TimeSeriesAnalysis}:-\mathrm{ExponentialSmoothingModel}\left(\mathrm{errors}\=\left\{''A''\right\}\,\mathrm{trend}\=\left\{''A''\right\}\,\mathrm{seasonal}\=\left\{''N''\right\}\,\mathrm{\α}\=0.999874595856735\,\mathrm{\β}\=0.21767056094623732\,\mathrm{\γ}\=0.\,\mathrm{\φ}\=1.\,\mathrm{period}\=1\,\mathrm{l0}\=17.560517881315064\,\mathrm{b0}\=0.34996342676412867\,s\=\left(\left[\begin{array}{c}0.0\end{array}\right]\right)\,\mathrm{\σ}\=0.06813734732902783\,\mathrm{constraints}\=''both''\right)$

$\mathrm{fc}≔\mathrm{Forecast}\left(\mathrm{esm}\,20\,\mathrm{output}\=\mathrm{confidenceintervals}\left(95\right)\right)$

$\mathrm{fc}≔\left[\begin{array}{c}\mathrm{Time\; series}\\ \mathrm{VALUE\; (forecast\; -\; 2\; percentile),\; VALUE\; (forecast\; -\; 50\; percentile),\; VALUE\; (forecast\; -\; 98\; percentile)}\\ \mathrm{20\; rows\; of\; data:}\\ \mathrm{2012-12-30\; -\; 2031-12-30}\end{array}\right]$

$\mathrm{TimeSeriesPlot}\left(\mathrm{fc}\,\mathrm{ref}\right)$

The DataSets[Quandl][Reference] command was introduced in Maple 2015.

For more information on Maple 2015 changes, see Updates in Maple 2015.