The python-pptx library is great for creating PowerPoint presentations programmatically, but it doesn’t support PowerPoint sections — the collapsible groups you see in the slide panel. This post shows how to add sections by directly manipulating the underlying XML with lxml.
The OOXML Structure
A .pptx file is a ZIP archive containing XML files. The presentation structure lives in ppt/presentation.xml. Sections are stored inside an extension element using the p14 namespace (http://schemas.microsoft.com/office/powerpoint/2010/main), not the standard p namespace.
The correct XML structure looks like this:
<p:extLst>
<p:ext uri="{521415D9-36F7-43E2-AB2F-B90AF26B5E84}">
<p14:sectionLst xmlns:p14="http://schemas.microsoft.com/office/powerpoint/2010/main">
<p14:section name="Introduction" id="{GUID-HERE}">
<p14:sldIdLst>
<p14:sldId id="256"/>
<p14:sldId id="257"/>
</p14:sldIdLst>
</p14:section>
<p14:section name="Background" id="{GUID-HERE}">
<p14:sldIdLst>
<p14:sldId id="258"/>
</p14:sldIdLst>
</p14:section>
<p14:section name="Proposed Method" id="{GUID-HERE}">
<p14:sldIdLst>
<p14:sldId id="259"/>
<p14:sldId id="260"/>
</p14:sldIdLst>
</p14:section>
<p14:section name="Conclusion" id="{GUID-HERE}">
<p14:sldIdLst/>
</p14:section>
</p14:sectionLst>
</p:ext>
</p:extLst>Key points:
p14:sectionLstmust be inside ap:extelement with URI{521415D9-36F7-43E2-AB2F-B90AF26B5E84}- That
p:extmust be insidep:extLst, which is a child ofp:presentation - Each
p14:sectionhas anameand a uniqueid(GUID format) - Each section contains a
p14:sldIdLstlisting the slide IDs that belong to it - Empty sections (no slides) use an empty
<p14:sldIdLst/>
Common Pitfall: Wrong Namespace
Why p14 and not p10?
The namespace URI contains “2010”: http://schemas.microsoft.com/office/powerpoint/2010/main. You might expect the prefix to be p10, but Microsoft uses p14 — it refers to PowerPoint 14.0 (the internal version number of Office 2010). This is a common source of confusion:
| OFFICE VERSION | INTERNAL VERSION | NAMESPACE PREFIX |
|---|---|---|
| Office 2010 | 14.0 | p14 |
| Office 2013 | 15.0 | p15 |
Using the standard p namespace (wrong)
If you place sections in the standard p namespace as a direct child of p:presentation:
<!-- WRONG — PowerPoint ignores this -->
<p:presentation>
...
<p:sectionLst>
<p:section name="Introduction" id="{GUID}">
<p:sldIdLst>
<p:sldId id="256"/>
</p:sldIdLst>
</p:section>
</p:sectionLst>
</p:presentation>PowerPoint will silently ignore it and show all slides in a “Default Section” instead. The file won’t be corrupted — the sections just won’t appear.
Python Implementation
Step 1: Create Slides with python-pptx
from pptx import Presentation
prs = Presentation("template.pptx")
# Add slides as usual
title_layout = prs.slide_masters[0].slide_layouts[0]
content_layout = prs.slide_masters[1].slide_layouts[0]
title_slide = prs.slides.add_slide(title_layout)
title_slide.shapes.title.text = "My Presentation"
intro_slide = prs.slides.add_slide(content_layout)
intro_slide.shapes.title.text = "Introduction"
bg_slide = prs.slides.add_slide(content_layout)
bg_slide.shapes.title.text = "Background"
method_slide1 = prs.slides.add_slide(content_layout)
method_slide1.shapes.title.text = "Proposed Method"
method_slide2 = prs.slides.add_slide(content_layout)
method_slide2.shapes.title.text = "Proposed Method (cont.)"
conclusion_slide = prs.slides.add_slide(content_layout)
conclusion_slide.shapes.title.text = "Conclusion"
# Remove template placeholder slides if needed
xml_slides = prs.slides._sldIdLst
for xml_slide in list(xml_slides[:2]):
xml_slides.remove(xml_slide)Step 2: Add Sections with lxml
from lxml import etree
def add_sections(prs, sections):
"""
Add sections to a PowerPoint presentation.
Args:
prs: python-pptx Presentation object
sections: list of dicts with 'name' and optional 'slide_ids'
e.g. [{"name": "Introduction", "slide_ids": ["256", "257"]},
{"name": "Background", "slide_ids": ["258"]}]
"""
presentation_elm = prs.part._element
P_NS = "http://schemas.openxmlformats.org/presentationml/2006/main"
P14_NS = "http://schemas.microsoft.com/office/powerpoint/2010/main"
SECTION_EXT_URI = "{521415D9-36F7-43E2-AB2F-B90AF26B5E84}"
nsmap_p = {"p": P_NS}
# Find or create extLst
extLst = presentation_elm.find("p:extLst", nsmap_p)
if extLst is None:
extLst = etree.SubElement(presentation_elm, f"{{{P_NS}}}extLst")
# Find or create the section extension element
section_ext = None
for ext in extLst.findall("p:ext", nsmap_p):
if ext.get("uri") == SECTION_EXT_URI:
section_ext = ext
break
if section_ext is None:
section_ext = etree.SubElement(
extLst, f"{{{P_NS}}}ext", uri=SECTION_EXT_URI
)
# Remove any existing sectionLst
for old in section_ext.findall(f"{{{P14_NS}}}sectionLst"):
section_ext.remove(old)
# Create new sectionLst
sectionLst = etree.SubElement(section_ext, f"{{{P14_NS}}}sectionLst")
# Add each section
for i, sec in enumerate(sections):
section_id = f"{{{i:08d}-0000-0000-0000-000000000001}}"
section = etree.SubElement(
sectionLst,
f"{{{P14_NS}}}section",
name=sec["name"],
id=section_id,
)
sldIdLst = etree.SubElement(section, f"{{{P14_NS}}}sldIdLst")
for sid in sec.get("slide_ids", []):
etree.SubElement(sldIdLst, f"{{{P14_NS}}}sldId", id=sid)Step 3: Get Slide IDs and Call
Slide IDs are numeric identifiers assigned by PowerPoint, not the slide index. You need to read them from the presentation XML:
nsmap_p = {"p": "http://schemas.openxmlformats.org/presentationml/2006/main"}
sldIdLst = prs.part._element.find(".//p:sldIdLst", nsmap_p)
slide_ids = [elem.get("id") for elem in sldIdLst]
# slide_ids is now e.g. ["256", "257", "258", "259", "260", "261"]
# Map them to your sections:
add_sections(prs, [
{"name": "Introduction", "slide_ids": slide_ids[:2]},
{"name": "Background", "slide_ids": [slide_ids[2]]},
{"name": "Proposed Method", "slide_ids": slide_ids[3:5]},
{"name": "Conclusion", "slide_ids": [slide_ids[5]]},
])
prs.save("output.pptx")Debugging
To verify sections are correctly written, inspect the XML inside the saved .pptx:
import zipfile
from lxml import etree
with zipfile.ZipFile("output.pptx") as z:
xml = z.read("ppt/presentation.xml")
root = etree.fromstring(xml)
print(etree.tostring(root, pretty_print=True).decode())Look for p14:sectionLst inside p:extLst → p:ext. If you see p:sectionLst as a direct child of p:presentation instead, sections won’t work.
Summary
| WHAT | HOW |
|---|---|
| Create slides | python-pptx as usual |
| Add sections | lxml — write p14:sectionLst inside p:extLst |
| Namespace | http://schemas.microsoft.com/office/powerpoint/2010/main (p14) |
| Extension URI | {521415D9-36F7-43E2-AB2F-B90AF26B5E84} |
| Assign slides | Reference slide IDs in each section’s p14:sldIdLst |
| Empty sections | Use <p14:sldIdLst/> with no children |
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