FrameView Class

public class FrameView

Public Class FrameView

public ref class FrameView

type FrameView = class end

Inheritance

Object    FrameView

Derived

Meta.Numerics.DataFrameTable

This is the central class for viewing data in our data frame system.

The methods of this class allow rows and columns of data to be re-ordered, filtered, manipulated, and analyzed. Most of the methods produce a new FrameView that presents a new view of the underlying data, without incurring the time and space costs of copying the underlying stored data.

The simplest data manipulations supported by views include filtering columns using Select and Discard and filtering rows using Where and WhereNotNull.

More advanced manipulations include the addition of computed columns using AddComputedColumnT(String, FuncFrameRow, T) and the computation of aggregate values of groups using GroupBy.

After you have created the view of your data that you want to analyze, the easiest way to hand individual columns of data to column-oriented analysis APIs (like those in the Meta.Numerics.Statistics namespace) is to use the ItemString accessor to get a column, together with the AsT caster to expose it as a collection of the required type. For example, to obtain a estimate of the mean of the population from the sample in the column named "heights", write view["height"].As<double>().PopulationMean(). Note that, for this to succeed, the underlying storage type of the heights column need not be double. As long as the data are convertible to the target type, no problems will arise. For example, the underlying storage type might be int, or double? as long as no null values are present in the view.

To create the original array of data that will be manipulated, use the FrameTable class. Note that, because the underlying data is not copied when a new view is generated, changes to the original table may have unexpected consequences for the views linked to it. Best practice is not to change the underlying data after generating views based on it.

You can export a view to CSV or JSON formats using the ToCsv(TextWriter) and ToDictionaries methods.

Reference