tBarChart - 6.1

Talend Components Reference Guide

EnrichVersion
6.1
EnrichProdName
Talend Big Data
Talend Big Data Platform
Talend Data Fabric
Talend Data Integration
Talend Data Management Platform
Talend Data Services Platform
Talend ESB
Talend MDM Platform
Talend Open Studio for Big Data
Talend Open Studio for Data Integration
Talend Open Studio for Data Quality
Talend Open Studio for ESB
Talend Open Studio for MDM
Talend Real-Time Big Data Platform
task
Data Governance
Data Quality and Preparation
Design and Development
EnrichPlatform
Talend Studio

tBarChart properties

Component family

Business Intelligence/Charts

 

Function

tBarChart reads data from an input flow and transforms the data into a bar chart in a PNG image file.

Purpose

tBarChart generates a bar chart from the input data to ease technical analysis.

Basic settings

Schema and Edit schema

A schema is a row description. It defines the number of fields (columns) to be processed and passed on to the next component. The schema is either Built-In or stored remotely in the Repository.

Since version 5.6, both the Built-In mode and the Repository mode are available in any of the Talend solutions.

Click Edit schema to make changes to the schema. If the current schema is of the Repository type, three options are available:

  • View schema: choose this option to view the schema only.

  • Change to built-in property: choose this option to change the schema to Built-in for local changes.

  • Update repository connection: choose this option to change the schema stored in the repository and decide whether to propagate the changes to all the Jobs upon completion. If you just want to propagate the changes to the current Job, you can select No upon completion and choose this schema metadata again in the [Repository Content] window.

Note

The schema of tBarChart contains three read-only columns named series (string), category (string), and value (integer) respectively, in a fixed order. The data in any extra columns will be only passed to the next component, if any, without being presented in the bar chart.

 

 

Built-in: The schema is created and stored locally for this component only. Related topic: see Talend Studio User Guide.

 

 

Repository: The schema already exists and is stored in the Repository, hence can be reused. Related topic: see Talend Studio User Guide.

 

Sync columns

Click to synchronize the output file schema with the input file schema. The Sync function only displays once the Row connection is linked with the output component.

 

Generated image path

Name and path of the output image file.

 

Chart title

Enter the title of the bar chart to be generated.

 

Include legend

Select this check box if you want the bar chart to include a legend, indicating all series in different colors.

 

3Dimensions

Select this check box to create an image with 3D effect. By default, this check box is selected and the bars representing the series of each category will be stacked one over another. If this check box is cleared, a 2D image will be created, with the bars displayed one besides another along the category axis.

 

Image width and Image height

Enter the width and height of the image file, in pixels.

 

Category axis name and Value axis name

Enter the category axis name and value axis name.

 

Foreground alpha

Enter an integer in the range of 0 to 100 to define the transparency of the image. The smaller the number you enter, the more transparent the image will be.

 

Plot orientation

Select the plot orientation of the bar chart: VERTICAL or HORIZONTAL.

Advanced settings

tStat Catcher Statistics

Select this check box to collect log data at the component level.

 

Enable parallel execution

Select this check box to perform high-speed data processing, by treating multiple data flows simultaneously. Note that this feature depends on the database or the application ability to handle multiple inserts in parallel as well as the number of CPU affected. In the Number of parallel executions field, either:

  • Enter the number of parallel executions desired.

  • Press Ctrl + Space and select the appropriate context variable from the list. For further information, see Talend Studio User Guide.

Warning

  • The Action on table field is not available with the parallelization function. Therefore, you must use a tCreateTable component if you want to create a table.

  • When parallel execution is enabled, it is not possible to use global variables to retrieve return values in a subjob.

Global Variables

NB_LINE: the number of rows read by an input component or transferred to an output component. This is an After variable and it returns an integer.

ERROR_MESSAGE: the error message generated by the component when an error occurs. This is an After variable and it returns a string. This variable functions only if the Die on error check box is cleared, if the component has this check box.

A Flow variable functions during the execution of a component while an After variable functions after the execution of the component.

To fill up a field or expression with a variable, press Ctrl + Space to access the variable list and choose the variable to use from it.

For further information about variables, see Talend Studio User Guide.

Usage

This component is mainly used as Output component. It requires an Input component and Row main link as input.

Scenario: Creating a bar chart from the input data

This scenario describes a Job that reads source data from a CSV file and transforms the data into a bar chart showing a comparison of several large cities. The input file is shown below:

City;Population(x1000);LandArea(km2);PopulationDensity(people/km2)
Beijing;10233;1418;7620
Moscow;10452;1081;9644
Seoul;10422;605;17215
Tokyo;8731;617;14151
Jakarta;8490;664;12738
New York;8310;789;10452

Because the input file has a different structure than the one required by the tBarChart component, this use case uses the tMap component to adapt the source data to the three-column schema of tBarChart so that a temporary CSV file can be created as the input to the tBarChart component.

Note

You will usually use the tMap component to adjust the input schema in accordance with the schema structure of the tBarChart component. For more information about how to use the tMap component, see Talend Studio User Guide and tMap.

To ensure correct generation of the temporary input file, a pre-treatment subjob is used to delete the temporary file in case it already exists before the main Job is executed; as this temporary file serves this specific Job only, a post-treatment subjob is used to deleted it after the main Job is executed.

Dropping and linking components

  1. Drop the following components from the Palette to the design workspace: a tPrejob, a tPostjob, two tFileDelete components, two tFileInputDelimited components, a tMap, three tFileOutputDelimited components, and a tBarChart.

  2. Connect the tPrejob component to one tFileDelete component using a Trigger > On Component Ok connection, and connect the tPostjob component to the other tFileDelete component using the same type of connection.

  3. Connect the first tFileInputDelimited to the tMap component using a Row > Main connection.

  4. Connect the tMap component to the first tFileOutputDelimited component using a Row > Main connection, and name the connection Population.

  5. Repeat the step above to connect the tMap component to the other two tFileOutputDelimited components using Row > Main connections, and name the connections Area and Density respectively.

  6. Connect the section tFileInputDelimited to the tBarChart component using a Row > Main connection.

  7. Connect the first tFileInputDelimited component to the second tFileInputDelimited component using a Trigger > On Subjob Ok connection.

  8. Relabel the components to best describe their functionality.

Reading the source data

  1. Double-click the first tFileInputDelimited component, which is labelled Large_Cities, to display its Basic settings view.

  2. Fill in the File name field by browsing to the input file.

  3. In the Header field, specify the number of header rows. In this use case, you have only one header row.

  4. Click Edit schema to describe the data structure of the input file. In this use case, the input schema is made of four columns: City, Population, Area, and Density. Upon defining the column names and data types, click OK to close the schema dialog box.

Adapting the source data to the tBarChart schema

  1. Double-click the tMap to open the Map Editor.

    You can see an input table on the input panel, row1 in this example, and three empty output tables, named Population, Area, and Density on the output panel.

  2. Use the Schema editor to add three columns to each output table: series (string), category (string), and value (integer).

  3. In the relevant Expression field of the output tables, enter the text to be presented in the legend area of the bar chart, "Population (x1000 people)", "Land area (km2)", and "Population density (people/km2)" respectively in this example.

  4. Drop the City column of the input table onto the category column of each output table.

  5. Drop the Population column of the input table onto the value column of the Population table.

  6. Drop the Area column of the input table onto the value column of the Area table.

  7. Drop the Density column of the input table onto the value column of the Density table.

  8. Click OK to save the mappings and close the Map Editor and propagate the output schemas to the output components.

Generating the temporary input file

  1. Double-click the first tFileOutputDelimited component to display its Basic settings view.

  2. In the File Name field, define a temporary CSV file to send the mapped data flows to. In this use case, we name this file Temp.csv. This file will be used as the input to the tBarChart component.

  3. Select the Append check box.

  4. Repeat the steps above to define the properties of the other two tFileOutputDelimited components, using exactly the same settings as in the first tFileOutputDelimited component.

    Note

    Note that the order of output flows from the tMap component is not necessarily the actual order of writing data to the target file. To ensure the target file is correctly generated, delete the file by the same name if it already exists before Job execution and select the Append check box in all the tFileOutputDelimited components in this step.

Configuring bar chart generation

  1. Double-click the second tFileInputDelimited component, which is labelled Temp_Input, to display its Basic settings view.

  2. Fill in the File name field with the path to the temporary input file generated by the tFileOutputDelimited components. In this use case, the temporary input file to the tBarChart is Temp.csv.

  3. Double-click the tBarChart component to display its Basic settings view.

  4. In the Generated image path field, define the file path of the image file to be generated.

  5. In the Chart title field, define a title for the bar chart.

  6. Define the category and series axis names.

  7. Define the size and transparency degree of the image if needed. In this use case, we simply use the default settings.

  8. Click Edit schema to open the schema dialog box.

  9. Copy all the columns from the output schema to the input schema by clicking the left-pointing double arrow button. Then, click OK to close the schema dialog box.

Deleting the temporary file

As the tPrejob and tPostjob components simply trigger the connected subjobs and do not have any settings to define, all you need to do is to define the properties of the two tFileDelete components.

  1. Double-click the first tFileDelete component to display its Basic settings view.

  2. Fill in the File name field with the path to the temporary input file.

    Note

    If the Fail on error check box is selected while the pre-treatment subjob fails because of errors such as the file to delete does not exist, this failure will prevent the main subjob from being launched. In this situation, you can clear the Fail on error check box to avoid this interruption.

  3. Specify the same file path in the other tFileDelete component.

Executing the Job

  1. Press Ctrl+S to save your Job.

  2. Press F6 to launch it.

    A bar chart is generated, showing a graphical comparison of the specified large cities.