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;10452Because 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.
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 Mapping data flows 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.