August 17, 2023

tBarChart – Docs for ESB 5.x

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tBarChart

tBarChart_icon32_white.png

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 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:

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.

use_case_tbarchart02.png

Reading the source data

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

    use_case_tbarchart03.png

  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.

    use_case_tbarchart04.png

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.

    use_case_tbarchart05.png

  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.

    use_case_tbarchart06.png

  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.

    use_case_tbarchart07.png

  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.

    use_case_tbarchart08.png

  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.

    use_case_tbarchart09.png

  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.

    use_case_tbarchart11.png

  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.

    use_case_tbarchart10.png
Document get from Talend https://help.talend.com
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Docs 5.x
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