"Introducing Missing Values"

cherokee

Hi!

How can I mark some value as missing?

I have some data where each feature (real-valued) of each instance has a value. Now I have mark some values as missing. How can I do this in RM?

Best regards,
chero

land

Hi,
this depends when you want to change the data? Before importing the data into RapidMiner or inside a RapidMiner process?

Greetings,
  Sebastian

cherokee

Hi!

I want to change it inside a RM process.

Best regards,
chero

land

Hi,
I would use the Generate Attributes operator for this. You might define conditions there to decide when a value should become unknown. Unfortunately this isn't encodable directly, but you could enter 0/0 to define a value as missing. Here's a sample process:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<process version="5.0">
  <context>
    <input>
      <location/>
    </input>
    <output>
      <location/>
      <location/>
    </output>
    <macros/>
  </context>
  <operator activated="true" class="process" expanded="true" name="Process">
    <parameter key="parallelize_main_process" value="true"/>
    <process expanded="true" height="595" width="366">
      <operator activated="true" class="generate_data" expanded="true" height="60" name="Generate Data" width="90" x="98" y="74"/>
      <operator activated="true" class="generate_attributes" expanded="true" height="76" name="Generate Attributes" width="90" x="246" y="75">
        <list key="function_descriptions">
          <parameter key="att1_new" value="if (att1 &gt; 3, 0/0, att1)"/>
        </list>
      </operator>
      <connect from_op="Generate Data" from_port="output" to_op="Generate Attributes" to_port="example set input"/>
      <connect from_op="Generate Attributes" from_port="example set output" 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>

Greetings,
  Sebastian

cherokee

Hi,

this is no solution to my problem. I use some program to encode specific data. This program doesn't allow to set some data as missing furthermore there is no value which i can use to mark some value as missing. The resulting data is written in a specific format.

I wrote my own RM operator to import this data. Now I have to say something like this: attribute 1 of example 13 is missing. This is NOT codeable in the data.

The only solution I see is importing it into RM and exporting it to csv (or similar). In that file I could give those attributes specific values which I could recode in RM the way you suggested. Is there an easier way.

Best regards,
chero

steffen

Hello

Since you have written your own input operator, setting missing values should be piece of cake for you :

Example example = <get-example-from-anywhere>;
example.setValue(<attribute>,Double.NaN);

Did you try that ? No guarantee for functionality, I am currently not able to test it.

steffen

cherokee

Hi!

I haven't tried it yet. But it seams to be the easiest solution. I'll give it a try in the next days.

Best regards,
chero