from cognite.client.data_classes import filters
from cognite.client.data_classes.documents import DocumentProperty
is_pdf = filters.Equals(DocumentProperty.mime_type, "application/pdf")
pdf_documents = client.documents.list(filter=is_pdf)

from cognite.client.data_classes.documents import DocumentProperty
for document in client.documents:
   print(document.name)

from cognite.client.data_classes.documents import SortableDocumentProperty
documents = client.documents.list(sort=(SortableDocumentProperty.mime_type, "desc"))

{
  "items": [
    {
      "id": 2384,
      "createdTime": 1519862400000,
      "sourceFile": {
        "name": "hamlet.txt",
        "directory": "plays/shakespeare",
        "source": "SubsurfaceConnectors",
        "mimeType": "application/octet-stream",
        "size": 1000,
        "hash": "23203f9264161714cdb8d2f474b9b641e6a735f8cea4098c40a3cab8743bd749",
        "assetIds": [],
        "labels": [
          {
            "externalId": "play"
          },
          {
            "externalId": "tragedy"
          }
        ],
        "geoLocation": {
          "type": "Point",
          "coordinates": [
            10.74609,
            59.91273
          ]
        },
        "datasetId": 4503599627370496,
        "securityCategories": [],
        "metadata": {}
      },
      "externalId": "haml001",
      "instanceId": {
        "space": "<string>",
        "externalId": "<string>"
      },
      "title": "Hamlet",
      "author": "William Shakespeare",
      "producer": "<string>",
      "modifiedTime": 1519958703000,
      "lastIndexedTime": 1521062805000,
      "mimeType": "text/plain",
      "extension": "pdf",
      "pageCount": 2,
      "type": "Document",
      "language": "en",
      "truncatedContent": "ACT I\nSCENE I. Elsinore. A platform before the castle.\n  FRANCISCO at his post. Enter to him BERNARDO\nBERNARDO\n  Who's there?\n",
      "assetIds": [
        42,
        101
      ],
      "labels": [
        {
          "externalId": "my.known.id"
        }
      ],
      "geoLocation": {
        "type": "Point",
        "coordinates": [
          10.74609,
          59.91273
        ]
      }
    }
  ],
  "nextCursor": "<string>"
}