Documentation updates for new filter UDFs.

- See: 
  - archivesunleashed/aut#430
  - archivesunleashed/aut#429
- Split filters documentation out in an RDD page, and DF page 
- Update root ToC

.github/workflows/main.yml

@@ -11,4 +11,4 @@ jobs:
     - name: Check out code
       uses: actions/checkout@master
     - name: Run mdl
-      uses: actionshub/markdownlint@master
+      uses: actionshub/markdownlint@master

current/README.md

@@ -59,7 +59,8 @@ Our documentation is divided into several main sections, which cover the Archive
 
 ### Filtering Results
 
-- **[Filters](filters.md)**: A variety of ways to filter results.
+- **[DataFrame Filters](filters-df.md)**:
+- **[RDD Filters](filters-rdd.md)**:
 
 ### Standard Derivatives
 
@@ -71,8 +72,8 @@ Our documentation is divided into several main sections, which cover the Archive
 
 ### What to do with Results
 
-- **[What to do with DataFrame Results](df-results.md)**
-- **[What to do with RDD Results](rdd-results.md)**
+- **[What to do with DataFrame Results](df-results.md)**: A variety of User Defined Functions for filters that can be used on any DataFrame column.
+- **[What to do with RDD Results](rdd-results.md)**: A variety of ways to filter RDD results 
 
 ## Further Reading
 

current/filters-df.md

@@ -0,0 +1,231 @@
+# Filters DataFrame
+
+The following UDFs (User Defined Functions) for filters can be used on any DataFrame column. In addition, each of the UDFs can be negated with `!`, e.g. `!hasImages`.
+
+**This column...**
+
+- [Has Content](#Has-Content)
+- [Has Date(s)](#Has-Dates)
+- [Has Domain(s)](#Has-Domains)
+- [Has HTTP Status](#Has-HTTP-Status)
+- [Has Images](#Has-Images)
+- [Has Language(s)](#Has-Languages)
+- [Has MIME Type (Apache Tika)](#Has-MIME-Type-Apache-Tika)
+- [Has MIME Type (web server)](#Has-MIME-Type-web-server)
+- [Has URL Pattern(s)](#Has-URL-Patterns)
+- [Has URL(s)](#Has-URLs)
+
+## Has Content
+
+Filters or removes all data that does or does not pass a specified regular expression test on content.
+
+### Scala DF
+
+```scala
+import io.archivesunleashed._
+import io.archivesunleashed.df._
+
+val content = Array("Content-Length: [0-9]{4}")
+
+RecordLoader.loadArchives("/path/to/warcs", sc)
+  .all()
+  .select("url", "content")
+  .filter(!hasContent($"content", lit(content)))
+```
+
+### Python DF
+
+**To be implemented.**
+
+## Has Dates
+
+Filters or keeps all data that does or does not match the date(s) specified.
+
+### Scala DF
+
+```scala
+import io.archivesunleashed._
+import io.archivesunleashed.df._
+
+val dates = Array("2008", "200908", "20070502")
+
+RecordLoader.loadArchives("/path/to/warcs",sc)
+  .all()
+  .select($"url", $"crawl_date")
+  .filter(!hasDate($"crawl_date", lit(dates)))
+```
+
+### Python DF
+
+**To be implemented.**
+
+## Has Domain(s)
+
+Filters or keeps all data that does or does not match the source domain(s) specified.
+
+### Scala DF
+
+```scala
+import io.archivesunleashed._
+import io.archivesunleashed.df._
+
+val domains = Array("www.archive.org", "www.sloan.org")
+
+RecordLoader.loadArchives("/path/to/warcs",sc)
+  .webpages()
+  .select($"url")
+  .filter(!hasDomains(ExtractDomainDF($"url"), lit(domains)))
+```
+
+### Python DF
+
+**To be implemented.**
+
+## Has HTTP Status
+
+Filters or keeps all data that does or does not match the status codes specified.
+
+### Scala DF
+
+```scala
+import io.archivesunleashed._
+import io.archivesunleashed.df._
+
+val statusCodes = Array("200","000")
+
+RecordLoader.loadArchives("/path/to/warcs",sc)
+  .all()
+  .select($"url",$"http_status_code")
+  .filter(!hasHTTPStatus($"http_status_code", lit(statusCodes)))
+```
+
+### Python DF
+
+**To be implemented.**
+
+## Has Images
+
+Filters or keeps all data except images. 
+
+### Scala DF
+
+```scala
+RecordLoader.loadArchives("/path/to/warcs",sc)
+  .all()
+  .select($"mime_type_tika", $"mime_type_web_server", $"url")
+  .filter(hasImages($"crawl_date", DetectMimeTypeTikaDF($"bytes")))
+```
+
+### Python DF
+
+**To be implemented.**
+
+## Has Languages
+
+Filters or keeps all data that does or does not match the language(s) ([ISO 639-2 codes](https://www.loc.gov/standards/iso639-2/php/code_list.php)) specified.
+
+### Scala DF
+
+```scala
+import io.archivesunleashed._
+import io.archivesunleashed.df._
+
+val languages = Array("th","de","ht")
+
+RecordLoader.loadArchives("/path/to/warcs",sc)
+  .webpages()
+  .select($"url", $"content")
+  .filter(hasLanguages(DetectLanguageDF(RemoveHTMLDF($"content")), lit(languages)))
+```
+
+### Python DF
+
+**To be implemented.**
+
+## Keep MIME Types (Apache Tika)
+
+Filters or keeps all data that does or does not match the MIME type(s) (identified by [Apache Tika](https://tika.apache.org/)) specified.
+
+### Scala DF
+
+```scala
+import io.archivesunleashed._
+import io.archivesunleashed.df._
+
+val mimeTypes = Array("text/html", "text/plain")
+
+RecordLoader.loadArchives("/path/to/warcs",sc)
+  .all()
+  .select($"url", $"mime_type_tika")
+  .filter(!hasMIMETypesTika($"mime_type_tika", lit(mimeTypes)))
+```
+
+### Python DF
+
+**To be implemented.**
+
+## Keep MIME Types (web server)
+
+Filters or keeps all data that does or does not match the MIME type(s) (identified by the web server) specified.
+
+### Scala DF
+
+```scala
+import io.archivesunleashed._
+import io.archivesunleashed.df._
+
+val mimeTypes = Array("text/html", "text/plain")
+
+RecordLoader.loadArchives("/path/to/warcs",sc)
+  .all()
+  .select($"url", $"mime_type_web_server")
+  .filter(!hasMIMETypesTika($"mime_type_web_server", lit(mimeTypes)))
+```
+
+### Python DF
+
+**To be implemented.**
+
+## Has URL Patterns
+
+Filters or removes all data that does or does not pass a specified regular expression test on URL patterns.
+
+### Scala DF
+
+```scala
+import io.archivesunleashed._
+import io.archivesunleashed.df._
+
+val urlsPattern = Array(".*images.*")
+
+RecordLoader.loadArchives("/path/to/warcs",sc)
+  .all()
+  .select($"url", $"content")
+  .filter(hasUrlPatterns($"url", lit(urlsPattern)))
+```
+
+### Python DF
+
+**To be implemented.**
+
+## Has URLs
+
+Filters or keeps all data that does or does not match the URL(s) specified.
+
+### Scala DF
+
+```scala
+import io.archivesunleashed._
+import io.archivesunleashed.df._
+
+val urls = Array("www.archive.org")
+
+RecordLoader.loadArchives("/path/to/warcs",sc)
+  .all()
+  .select($"url", $"content")
+  .filter(hasUrls($"url", lit(urls)))
+```
+
+### Python DF
+
+**To be implemented.**