# Text Preprocessing

Text preprocessing is done to remove unwanted characters, words or lines from the document before the extraction or classification is done. Although it is not a necessary step , adding text preprocessors will increase the accuracy of the task. Text preprocessors can be added only in [Regex Extractor](/getting-started/rpa-studio/document-ai/document-extractor/types/regex-extractor.md) and [Keyword Classifier](/getting-started/rpa-studio/document-ai/document-classifier/types/keyword-classifier.md).

{% hint style="info" %}
Preprocessing is applied in the order they appears in the preprocessors list. If there are two preprocessors, then the second preprocessor gets the output of the first preprocessor. 
{% endhint %}

**Line**

1. **Remove Lines**\
   Removes the specified lines.
   * **Contains**\
     Removes the lines which contains the specified words.
   * **Starts With**\
     Removes the lines which starts with the specified word.
   * **Ends With**\
     Removes the lines which ends with the specified word.
   * **With line numbers**\
     Remove all the lines with the specified line number. For example to remove the First, third and Ninth lines specify the input as 1,9,10.

**Text**

1. **Replace Text**\
   Replaces the text or the text matched by the regular expression with the specified text.
2. **Remove Text**\
   Removes the text or the text matched by the regular expression.
3. **Remove from list**\
   Removes the list of words selected from a text file.

**Character**

1. **Remove Character**\
   Removes all the specified characters from the document text. For example to remove all ‘$’ , ‘5’ and ‘#’ characters, specify the input as ‘$#5’.


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