Fetching data from two different sheets of excel in rapidminer - excel

Question

I am a beginner in rapidminer. I am working on a project where I need to work on multiple sheets of excel say A and B. There is some data which is present in sheet A, and I have to use this data and perform arithmetic operations on it and some data from sheet B and produce results in sheet B.
I am using read excel operator for fetching excel sheet. And I am using generate attributes to perform arithmetic operations. I found loop operator is used when we are dealing with multiple sheets. But it requires that all the column names of all the sheets should be same. In my case, they are not. So what should I do? How to use multiple sheets when they don't have same column names?
Thanks

Answer 1

The Select Subprocess operator lets you choose a different subprocess based on the value of its select which parameter. Within your Loop operator you are likely to have a macro containing the sheet you are importing. This macro can be used as the parameter for select which. Inside the Select Subprocess operator, the corresponding subprocess will be executed. Obviously, it's up to you to get the contents of each subprocess correct.

Answer 2

There's a small trick with the RapidMiner Read Excel operator that you might not know.
If you don't configure it, but instead just point it at the Excel file you want then it will attempt to import everything from the sheet in sheet number, despite the imported cell range A1.
Use this with the loop operator to bring the data in & store them as individual examplesets in the repository. (You can also use Select Subprocess as Andrew mentioned to perform Generate Attributes just on Sheet1)
Here's an example process.
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<process version="7.0.000">
<context>
<input/>
<output/>
<macros/>
</context>
<operator activated="true" class="process" compatibility="7.0.000" expanded="true" name="Process">
<process expanded="true">
<operator activated="true" class="loop" compatibility="7.0.000" expanded="true" height="82" name="Loop" width="90" x="112" y="85">
<parameter key="set_iteration_macro" value="true"/>
<parameter key="macro_name" value="sheetNum"/>
<parameter key="iterations" value="2"/>
<process expanded="true">
<operator activated="true" class="read_excel" compatibility="7.0.000" expanded="true" height="68" name="Read Excel" width="90" x="112" y="85">
<parameter key="excel_file" value="C:\Users\user\myExcel.xlsx"/>
<parameter key="sheet_number" value="%{sheetNum}"/>
<list key="annotations"/>
<list key="data_set_meta_data_information"/>
<description align="center" color="orange" colored="true" width="126">Read each sheetNum. Note this operator is not configured with attribute names it reads these from the Excel doc.</description>
</operator>
<operator activated="true" class="store" compatibility="7.0.000" expanded="true" height="68" name="Store" width="90" x="313" y="85">
<parameter key="repository_entry" value="//Local Repository/data/myExcel_sheet%{sheetNum}"/>
<description align="center" color="orange" colored="true" width="126">Store each sheetNum as a separate ExampleSet in the repository.</description>
</operator>
<connect from_op="Read Excel" from_port="output" to_op="Store" to_port="input"/>
<connect from_op="Store" from_port="through" to_port="output 1"/>
<portSpacing port="source_input 1" spacing="0"/>
<portSpacing port="sink_output 1" spacing="0"/>
<portSpacing port="sink_output 2" spacing="0"/>
</process>
<description align="center" color="orange" colored="true" width="126">Loop 2 times for each sheetNum</description>
</operator>
<connect from_op="Loop" from_port="output 1" to_port="result 1"/>
<portSpacing port="source_input 1" spacing="0"/>
<portSpacing port="sink_result 1" spacing="0"/>
<portSpacing port="sink_result 2" spacing="0"/>
</process>
</operator>
</process>