August 17, 2023

tLineChart – Docs for ESB 5.x

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tLineChart

tLineChart_icon32_white.png

tLineChart properties

Component family

Business Intelligence/Charts

  

Function

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

Purpose

tLineChart generates a line 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.

Note

The schema of tLineChart
contains three read-only columns named series (string), x (integer), and y (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 generated line
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 line chart to be generated.

 

Domain axis label and Range axis
label

Enter the domain axis (X axis) and range axis (Y axis)
labels.

 

Plot orientation

Select the plot orientation of the range axis: Vertical or Horizontal.

 

Include legend

Select this check box if you want your line chart to include a
legend, indicating the lines of different series in different
colors.

 

Image width and Image
height

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

 

Moving average

Select this check box to show a moving average for each series on
your line chart. With this check box selected, the Period field appears, letting you define
a period of which you want to show the moving average.

 

Lower bound and Upper
bound

Define the lowest and highest values to be displayed on the range
axis.

 

Chart background and Plot
background

Select the chart background color and the plot area background
color.

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 line chart to ease trend analysis

This scenario describes a Job that reads data from a CSV file and transforms the data
into a line chart to facilitate trend analysis. The input file records how long (in
minutes) per week a person watches different TV channels over ten weeks, as shown
below:

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

Note

You will usually use the tMap component to adjust
the input schema in accordance with the schema structure of the tLineChart 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: two tFileDelete components, two tFileInputDelimited components, a tMap, three tFileOutputDelimited components, and a tLineChart.

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

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

  4. Repeat the step above to connect the tMap
    component to the other two tFileOutputDelimited components using Row > Main connections, and
    name the connections TV_B and TV_C respectively.

  5. Connect the section tFileInputDelimited
    to the tLineChart component using a
    Row > Main connection. When questioned whether to get the schema
    from the target component, click Yes.

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

  7. Connect the first tFileDelete component
    to the first tFileInputDelimited component,
    and then the second tFileInputDelimited
    component to the second tFileDelete
    component, using Trigger > On Subjob Ok connections.

  8. Relabel the components to best describe their functionality.

use_case_tlinechart02.png

Reading the source data

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

    use_case_tlinechart03.png

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

  3. Specify the header row. In this use case, the first row of the input file
    is the header row. And leave the other parameters as they are.

  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: Week, Mins_TVA,
    Mins_TVB, and Mins_TVC. Upon
    defining the column names and data type, click OK to close the schema dialog box.

    use_case_tlinechart04.png

Adapting the source data to the tLineChart 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
    TV_A, TV_B, and TV_C on the
    output panel.

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

  3. In the relevant Expression field of the
    output tables, enter the text to be presented in the legend area of the line
    chart, TV A, TV B, and TV C
    respectively in this example.

  4. Drop the Week column of the input table onto the
    x column of each output table.

  5. Drop the Mins_TVA column of the input table onto the
    y column of the TV_A table.

  6. Drop the Mins_TVB column of the input table onto the
    y column of the TV_B table.

  7. Drop the Mins_TVC column of the input table onto the
    y column of the TV_C table.

    use_case_tlinechart05.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_tlinechart06.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 tLineChart 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, we need to 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 line chart generation

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

    use_case_tlinechart07.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 tLineChart is
    Temp.csv.

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

    use_case_tlinechart08.png

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

    use_case_tlinechart09.png

  5. Check that the input and output schemas are synchronized. If needed, 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.

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

  7. In the Chart title field, define a title
    for the line chart. In this use case, enter Average Weekly Viewing
    (per person)     as the chart title.

  8. Define the domain (X) and range (Y) axis labels. In this use case, enter
    Week and Minutes respectively the axis
    labels.

  9. Define the image size, the moving average period, the lower and upper
    bounds, the chart background color, and the background color of the plot
    area, as you prefer.

    In this use case, we set the image size to 450 by
    450, set the lower and upper bounds to 210 and
    340 respectively, select light
    gray     as the chart background color, and keep the rest
    settings are they are.

Deleting the temporary file

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

    use_case_tlinechart11.png

  2. Fill in the File name field with the path
    to the temporary input file, and clear the Fail on
    error     check box to allow the main Job to be executed if the
    file to delete does not exist.

  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 the Job.

    A line chart is generated as defined, showing a graphical comparison of
    the average weekly viewing time and the viewing trends of different TV
    channels over the past ten weeks.

    use_case_tlinechart10.png
Document get from Talend https://help.talend.com
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Docs 5.x
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