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Truncation

As explained in Starting Data Analytics with Generative AI and Python

Truncation is the removal of input tokens that exceed a model's permitted context length.

Truncation removes tokens that exceed a model’s context window. Because the window includes both prompt and response tokens, earlier conversation or input can disappear without warning, leaving the model inconsistent with prior exchanges. section 1.1 section 1.3.2

The overheard conversation

Imagine someone hearing only the last two sentences of a long conversation and then offering advice. When truncation removes earlier tokens, an AI can respond similarly: it may lose crucial instructions, context, or large portions of supplied code. section 1.3.2

Reduce the risk of losing important context by:

  • Estimating token usage and remembering that tokenization differs between models. section 1.1 section 1.3.2
  • Chunking long inputs into segments that fit the context window while retaining enough local context. section 1.3.2
  • Using sliding windows, iterative refinement, summaries, or external memory to preserve relevant information across segments. section 1.1 section 1.3.2

How Starting Data Analytics with Generative AI and Python covers it

How deep it goes
Explains token limits, earliest-token removal, symptoms, and mitigation strategies, but does not detail token-counting implementation.
Examples
Uses an overheard-conversation analogy and warns that truncation is particularly dangerous for large code inputs.
What it assumes
Assumes familiarity with generative AI conversations and teaches that words are represented as model-specific tokens.
What you can do after
Diagnose forgotten context and preserve relevant information by chunking inputs or summarizing conversations.
How it connects
Connects truncation with context windows, tokenization, chunking, sliding windows, iterative refinement, summaries, and external memory.

Related concepts

This explainer was generated by Manning's knowledge graph from the text of Starting Data Analytics with Generative AI and Python. The section links point to the parts of the book it draws on.