4  Structured Output

library(rtemis.llm)

  .:rtemis.llm v.0.8.0 🌊 aarch64-apple-darwin20

rtemis.llm provides convenience functions schema() and field() to define structured output schemas for LLM responses.

4.1 Define a schema

city_schema <- schema(
  name = "CitySchema",
  field("name", "Official city name in English", "string"),
  field("country", "Country where the city is located", "string"),
  field("population", "Population of the city", "number")
)
city_schema

CitySchema: 
            description: NULL
                 fields: 
                               name: 
                                            type: string
                                     description: Official city name in English
                                        required: TRUE
                            country: 
                                            type: string
                                     description: Country where the city is located
                                        required: TRUE
                         population: 
                                            type: number
                                     description: Population of the city
                                        required: TRUE
 

4.2 LLM: Generate structured output

4.2.1 LLM with output_schema

llm <- create_Ollama(
  model_name = "gemma4:e4b",
  system_prompt = "You are an expert intelligence analyst. Respond in the format specified by the provided schema.",
  temperature = 0.2,
  output_schema = city_schema
)
llm

<Ollama>
        Model: gemma4:e4b
System Prompt: You are an expert intelligence analyst. Respond in the format specified by the provided schema.
  Temperature: 0.2
Output Schema: 
               CitySchema: 
                           description: NULL
                                fields: 
                                              name: 
                                                           type: string
                                                    description: Official city name in English
                                                       required: TRUE
                                           country: 
                                                           type: string
                                                    description: Country where the city is located
                                                       required: TRUE
                                        population: 
                                                           type: number
                                                    description: Population of the city
                                                       required: TRUE
 

generate(llm, "Tell me about Tokyo.")

2026-04-23 18:01:12 [gemma4:e4b] working... [generate]
2026-04-23 18:01:14 [gemma4:e4b] done. [generate]

[Response] {
  "name": "Tokyo",
  "country": "Japan",
  "population": 37470000.0000000000000000e+0
  } 

4.2.2 generate() with output_schema

llm <- create_Ollama(
  model_name = "gemma4:e4b",
  system_prompt = "You are an expert intelligence analyst. Respond in the format specified by the provided schema.",
  temperature = 0.2
)
llm

<Ollama>
        Model: gemma4:e4b
System Prompt: You are an expert intelligence analyst. Respond in the format specified by the provided schema.
  Temperature: 0.2
 

generate(llm, "Tell me about Honolulu.", output_schema = city_schema)

2026-04-23 18:01:14 [gemma4:e4b] working... [generate]
2026-04-23 18:01:16 [gemma4:e4b] done. [generate]

[Response] {
  "name": "Honolulu",
  "country": "United States",
  "population": 319322.0000000000577353
  } 

output_schema is similary supported in create_agent() and generate() for Agent objects.

4.3 map() with output_schema

ColorSchema <- schema(
  name = "ColorSchema",
  field("color_name", "Name of the color", "string"),
  field("hex_code", "Hex code of the color in format #RRGGBB", "string")
)
llm <- create_Ollama(
  model_name = "gemma4:e4b",
  system_prompt = "Return the hex code for the following color in format #RRGGBB",
  temperature = 0.2
)
x <- c("ocean teal", "california poppy orange", "bougainvillea pink")

hex <- map(x, llm, output_schema = ColorSchema)

2026-04-23 18:01:16 [gemma4:e4b] working... [map]
2026-04-23 18:01:20 [gemma4:e4b] done. [map]

hex

[[1]]
[Response] {
  "color_name": "ocean teal",
  "hex_code": "#008080"
} 

[[2]]
[Response] {
  "color_name": "California Poppy Orange",
  "hex_code": "#FF9933"
} 

[[3]]
[Response] {
  "color_name": "bougainvillea pink",
  "hex_code": "#E86A8B"
}