Search for specific pattern within strings of characters

komal_chenthama

Hi,

 

I have a table with 1000s of rows, with long string of characters without spaces. An example of such a single row is below:

 

"MKFFAAAALFATSAMAAVCPDGGLFSNPLCCSSILLEAVGLDCTTPTAPVVTAGLFQANCASIGKQPACCVAPLAGQGILCNNPAGT"

 

I would like to filter out all the rows in my table that have following pattern C...CC...C..C..CC..C, where "." represents any character any number of times. Could anyone kindly suggest an operator or combinaton of operators for this task?

 

rfuentealba

Hi @komal_chenthama

 

The Filter Examples operator allows you to match by a regular expression. I can build one to give you an example. In your question, C means... the character "C" or it can be any character?

 

@sgenzer (do you mind if I write a tutorial on regular expressions with RapidMiner, to be included in the RapidMiner documentation?)

 

All the best,

 

Rodrigo.

MartinLiebig

Hi @komal_chenthama,

 

Filter Examples with expression and matches(..) is the way to go. Attached is an example process.

~Martin

 

<?xml version="1.0" encoding="UTF-8"?><process version="8.2.000">
  <context>
    <input/>
    <output/>
    <macros/>
  </context>
  <operator activated="true" class="process" compatibility="8.2.000" expanded="true" name="Process">
    <process expanded="true">
      <operator activated="true" class="generate_data_user_specification" compatibility="8.2.000" expanded="true" height="68" name="Generate Data by User Specification" width="90" x="112" y="136">
        <list key="attribute_values">
          <parameter key="string" value="&quot;MKFFAAAALFATSAMAAVCPDGGLFSNPLCCSSILLEAVGLDCTTPTAPVVTAGLFQANCASIGKQPACCVAPLAGQGILCNNPAGT&quot;"/>
        </list>
        <list key="set_additional_roles"/>
      </operator>
      <operator activated="true" class="filter_examples" compatibility="8.2.000" expanded="true" height="103" name="Filter Examples" width="90" x="246" y="136">
        <parameter key="parameter_expression" value="matches(string,&quot;C.+.+.+CC.+.+.+C.+.+C.+.+CC.+.+C&quot;)"/>
        <parameter key="condition_class" value="expression"/>
        <list key="filters_list"/>
      </operator>
      <connect from_op="Generate Data by User Specification" from_port="output" to_op="Filter Examples" to_port="example set input"/>
      <connect from_op="Filter Examples" 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>

komal_chenthama

Hi @rfuentealba

 

Thanks for the quick response. In my example, I mean particularly the character "C". 

 

Cheers,

Komal

 

PS: I would very much appreciate a tutorial on regular expression with RapidMiner.

 

rfuentealba

Hi @komal_chenthama

 

The regular expression you are looking for is pretty simple:

 

C(.+)CC(.+)C(.+)C(.+)CC(.+)C

 

Here is a capture on how it works when using it on the "Replace Operator".

 

See? It recognizes only the patterns you want.

 

Hope it helps.