Remove or replace URL and RT from Twitter dataset

Hello everyone!

So right now I'm trying to do a data cleaning phase on text classification using Twitter dataset. But I have a problem about how to replace (or maybe remove) the URL, RT and @ character. I've read some post on the forum but I didn't understand anything :catsad:

For the URL on the dataset, I want to change the format from "https:" or "http:" to "link" (I don't know why it can't have a null value like " "). But after I executed my process using Replace operator, the result from "http://blablabla" didn't change into "link" only, but the result come out like this "linkblablabla". Maybe it has something to do with the RegEx? :catsad: I know what's RegEx but I don't how how to use and write it :catsad:

I'm really confused right now. Please help me.

This's my RapidMiner process :

<?xml version="1.0" encoding="UTF-8"?><process version="8.1.001">
  <context>
    <input/>
    <output/>
    <macros/>
  </context>
  <operator activated="true" class="process" compatibility="8.1.001" expanded="true" name="Process">
    <process expanded="true">
      <operator activated="true" class="retrieve" compatibility="8.1.001" expanded="true" height="68" name="Retrieve Dataset Skripsi" width="90" x="45" y="34">
        <parameter key="repository_entry" value="Dataset Skripsi"/>
      </operator>
      <operator activated="true" class="nominal_to_text" compatibility="8.1.001" expanded="true" height="82" name="Nominal to Text" width="90" x="179" y="34">
        <parameter key="attribute_filter_type" value="single"/>
        <parameter key="attribute" value="Text"/>
      </operator>
      <operator activated="true" class="set_role" compatibility="8.1.001" expanded="true" height="82" name="Set Role" width="90" x="313" y="34">
        <parameter key="attribute_name" value="Label"/>
        <parameter key="target_role" value="label"/>
        <list key="set_additional_roles"/>
      </operator>
      <operator activated="true" class="filter_examples" compatibility="8.1.001" expanded="true" height="103" name="Filter Examples" width="90" x="447" y="34">
        <parameter key="condition_class" value="no_missing_attributes"/>
        <list key="filters_list"/>
      </operator>
      <operator activated="true" class="remove_duplicates" compatibility="8.1.001" expanded="true" height="103" name="Remove Duplicates" width="90" x="581" y="34">
        <parameter key="attribute_filter_type" value="single"/>
        <parameter key="attribute" value="Text"/>
      </operator>
      <operator activated="true" class="replace" compatibility="8.1.001" expanded="true" height="82" name="Replace" width="90" x="715" y="34">
        <parameter key="replace_what" value="(https://)"/>
        <parameter key="replace_by" value="link"/>
      </operator>
      <connect from_op="Retrieve Dataset Skripsi" from_port="output" to_op="Nominal to Text" to_port="example set input"/>
      <connect from_op="Nominal to Text" from_port="example set output" to_op="Set Role" to_port="example set input"/>
      <connect from_op="Set Role" from_port="example set output" to_op="Filter Examples" to_port="example set input"/>
      <connect from_op="Filter Examples" from_port="example set output" to_op="Remove Duplicates" to_port="example set input"/>
      <connect from_op="Remove Duplicates" from_port="example set output" to_op="Replace" to_port="example set input"/>
      <connect from_op="Replace" 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>

I need your help. Thank you!