ASP.NET 4 Unleased - p 71 docx

Sorting and Filtering Data An instance of a chart control contains a DataManipulator property that can be used to sort and filter the chart data.. The DataManipulator property provides a

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Area—Shows the rate of change over time by shading the area under the line

Bar—Similar to a Column chart but displays the values horizontally instead of

vertically

Line—Displays changes in data by rendering data points as a single continuous line

Point—Displays each value as a point on the chart

Pie—Shows how much each data point contributes to the entire data set by

render-ing it as a percentage

Box Plot—Shows how data is distributed across a data set by displaying one or more

boxes

Candlestick—Commonly used to display stock information, such as the high and

low values, along with the opening and closing prices

NOTE

You can find the complete set of possible chart types on the MSDN website at

http://msdn.microsoft.com/en-us/library/dd489233(VS.100).aspx

Sorting and Filtering Data

An instance of a chart control contains a DataManipulator property that can be used to

sort and filter the chart data You can sort any series in the chart by any axis (X, Y, Y2,

and so on), and you can choose to sort in either an ascending or descending order The

DataManipulator property provides a Sort method to do this

To use the sorting functionality, your chart must already be populated with data To

ensure this, we wait until the OnDataBound event to invoke our sorting code Listing 15.3

sorts the movie categories from highest count to lowest count by executing the

chtMovies_DataBound method after it binds to the SqlDataSource (see Figure 15.3)

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<%@ Page Language=”C#” %>

<%@ Register Assembly=”System.Web.DataVisualization,

Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35”

Namespace=”System.Web.UI.DataVisualization.Charting”

TagPrefix=”asp” %>

<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.1//EN”

“http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd”>

void chtMovies_DataBound(object sender, EventArgs e)

{

chtMovies.DataManipulator.Sort(PointSortOrder.Descending, “Y”,

➥“MovieCategorySeries”);

}

</script>

<title>Show Chart</title>

</head>

<body>

<div>

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<asp:Chart ID=”chtMovies” runat=”server” DataSourceID=”srcMovies”

OnDataBound=”chtMovies_DataBound”>

<asp:Series Name=”MovieCategorySeries” XValueMember=”Category”

YValueMembers=”Count”>

</asp:Series>

</Series>

<asp:ChartArea Name=”MovieChartArea”>

</asp:ChartArea>

</ChartAreas>

</asp:Chart>

<asp:SqlDataSource ID=”srcMovies” ConnectionString=”<%$

➥ConnectionStrings:Movies %>”

SelectCommand=”CountMoviesInCategory”

SelectCommandType=”StoredProcedure” runat=”server” />

</div>

</form>

</body>

</html>

Filtering chart data is similar to sorting it The DataManipulator provides a FilterTopN

method that enables you to only display the top “n” number of data points For

example, Listing 15.4 shows only the three movie categories with the highest counts (see

Figure 15.4)

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Namespace=”System.Web.UI.DataVisualization.Charting”

TagPrefix=”asp” %>

{

chtMovies.DataManipulator.FilterTopN(3, “MovieCategorySeries”,

“MovieCategorySeries”, “Y”, true);

}

</script>

</head>

<body>

<div>

<asp:Series Name=”MovieCategorySeries” XValueMember=”Category”

YValueMembers=”Count”>

</asp:Series>

</Series>

</asp:ChartArea>

</ChartAreas>

</asp:Chart>

<asp:SqlDataSource ID=”srcMovies” ConnectionString=”<%$

➥ConnectionStrings:Movies %>”

SelectCommand=”CountMoviesInCategory” SelectCommandType=”StoredProcedure”

runat=”server” />

</div>

</form>

</body>

</html>

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NOTE

It is also possible to define custom sorts and filters for your chart The

DataManipulator provides a Sort method that takes an object of type IComparer as

a parameter, along with a Filter method that takes an object of type

IDataPointFilter as a parameter You can write classes that implement these

inter-faces and build the logic that sorts or filters your data however you like

Using Statistical Formulas

Statistical analysis goes hand in hand with charting and data visualization, and the

ASP.NET charting control provides a wealth of functionality in this area The

DataManipulator property makes it easy to add statistical analyses to your charts You can

use the Statistics property on the DataManipulator to perform statistical analyses on

data series without having to hand-write custom algorithms (Though you can do that

too, if necessary.)

The code in Listing 15.5 illustrates adding a label to the top of a page that contains a chart

showing the mean value of a series of data points (see Figure 15.5)

Namespace=”System.Web.UI.DataVisualization.Charting” TagPrefix=”asp” %>

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{

lblAverage.Text =

chtMovies.DataManipulator.Statistics.Mean(“MovieCategorySeries”).ToString();

}

</script>

</head>

<body>

<div>

<p>Average Number of Movies In a Category: <asp:Label ID=”lblAverage”

➥runat=”server” /></p>

<asp:Series Name=”MovieCategorySeries”

XValueMember=”Category” YValueMembers=”Count” >

</asp:Series>

</Series>

</asp:ChartArea>

</ChartAreas>

</asp:Chart>

<asp:SqlDataSource

id=”srcMovies”

ConnectionString=”<%$ ConnectionStrings:Movies %>”

SelectCommandType=”StoredProcedure”

Runat=”server” />

</div>

</form>

</body>

</html>

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You can also use these calculated statistics to display strip lines—a band across any axis to

bring attention to a value or range of values Strip lines can be defined declaratively on

any axis within ChartArea Listing 15.6 adds a strip line to display the average count

(mean) within the chart by declaring a StripLine on the AxisY axis (see Figure 15.6)

{

double average =

➥chtMovies.DataManipulator.Statistics.Mean(“MovieCategorySeries”);

lblAverage.Text = average.ToString();

chtMovies.ChartAreas[“MovieChartArea”].AxisY.StripLines[0].IntervalOffset =

average;

}

</script>

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</head>

<body>

<div>

<p>Average Number of Movies In a Category: <asp:Label ID=”lblAverage”

➥runat=”server” /></p>

<asp:Series Name=”MovieCategorySeries”

XValueMember=”Category” YValueMembers=”Count” >

</asp:Series>

</Series>

<AxisY>

<asp:StripLine BorderColor=”Orange” BorderWidth=”2” />

</StripLines>

</AxisY>

</asp:ChartArea>

</ChartAreas>

</asp:Chart>

<asp:SqlDataSource

id=”srcMovies”

ConnectionString=”<%$ ConnectionStrings:Movies %>”

SelectCommandType=”StoredProcedure”

Runat=”server” />

</div>

</form>

</body>

</html>

The Statistics property provides common formulas such as mean, median, normal

distribution, correlation, and covariance Advanced calculations specific to financial

analy-ses can be performed by using the FinancialFormula method on the DataManipulator

object Some common financial formulas that can be calculated with the

FinancialFormula method follow:

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MovingAverage—An average of data calculated over a period of time

ExponentialMovingAverage—Similar to a MovingAverage, except recent days have

more weight in the calculation

Forecasting—Predicts the future values by analyzing the historical data

MassIndex—Predicts the reversal of a trend by comparing the difference and range

between the high and low values in a dataset

StandardDeviation—Calculates the difference between values in a dataset

Listing 15.7 demonstrates how to perform financial analysis on a sample set of data and

display it as a series (see Figure 15.7)

void PopulateData()

{

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chtPrices.Series[“PriceSeries”].Points.AddXY(“2/1/2010”, 50);

}

void Page_Load()

{

PopulateData();

chtPrices.DataManipulator.FinancialFormula(FinancialFormula.Forecasting,

“Exponential,3,false,false”, “PriceSeries”, “ForecastSeries”);

}

</script>

</head>

<body>

<div>

<asp:Chart ID=”chtPrices” runat=”server” >

<asp:Series Name=”PriceSeries” ChartType=”Line” Color=”Red”

BorderWidth=”2”></asp:Series>

<asp:Series Name=”ForecastSeries” ChartType=”Line”

➥Color=”Blue”></asp:Series>

</Series>

<asp:ChartArea Name=”PriceChartArea”>

<AxisY>

</AxisY>

</asp:ChartArea>

</ChartAreas>

</asp:Chart>

</div>

</form>

</body>

</html>

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