Claude API: Komplet Guide til Danske Udviklere

1import anthropic
2
3client = anthropic.Anthropic()  # Uses ANTHROPIC_API_KEY env var
4
5message = client.messages.create(
6    model="claude-sonnet-4-20250514",
7    max_tokens=1024,
8    messages=[
9        {"role": "user", "content": "Hvad er forskellen mellem REST og GraphQL?"}
10    ]
11)
12
13print(message.content[0].text)
14print(f"Input tokens: {message.usage.input_tokens}")
15print(f"Output tokens: {message.usage.output_tokens}")

1message = client.messages.create(
2    model="claude-sonnet-4-20250514",
3    max_tokens=1024,
4    system="""Du er en senior software arkitekt.
5Svar altid med:
61. En kort forklaring
72. Kodeeksempel hvis relevant
83. Potentielle pitfalls
9
10Hold svarene koncise og tekniske. Brug dansk.""",
11    messages=[
12        {"role": "user", "content": "Hvordan implementerer jeg dependency injection i Python?"}
13    ]
14)

1from typing import List, Dict
2
3class Conversation:
4    def __init__(self, system_prompt: str = None):
5        self.messages: List[Dict] = []
6        self.system = system_prompt
7        self.client = anthropic.Anthropic()
8
9    def chat(self, user_message: str) -> str:
10        self.messages.append({"role": "user", "content": user_message})
11
12        response = self.client.messages.create(
13            model="claude-sonnet-4-20250514",
14            max_tokens=2048,
15            system=self.system,
16            messages=self.messages
17        )
18
19        assistant_message = response.content[0].text
20        self.messages.append({"role": "assistant", "content": assistant_message})
21
22        return assistant_message
23
24    def clear(self):
25        self.messages = []
26
27# Usage
28conv = Conversation(system_prompt="Du er en Python ekspert.")
29print(conv.chat("Forklar list comprehensions"))
30print(conv.chat("Giv mig et komplekst eksempel"))  # Husker konteksten

1# Simple streaming
2with client.messages.stream(
3    model="claude-sonnet-4-20250514",
4    max_tokens=1024,
5    messages=[{"role": "user", "content": "Skriv en kort historie om en robot"}]
6) as stream:
7    for text in stream.text_stream:
8        print(text, end="", flush=True)
9
10# Streaming with events
11with client.messages.stream(
12    model="claude-sonnet-4-20250514",
13    max_tokens=1024,
14    messages=[{"role": "user", "content": "Forklar quantum computing"}]
15) as stream:
16    for event in stream:
17        if event.type == "content_block_delta":
18            print(event.delta.text, end="", flush=True)
19        elif event.type == "message_stop":
20            print("\n--- Done ---")
21
22# Get final message after streaming
23response = stream.get_final_message()
24print(f"\nTotal tokens: {response.usage.input_tokens + response.usage.output_tokens}")

1import json
2
3# Define tools
4tools = [
5    {
6        "name": "get_weather",
7        "description": "Hent vejret for en given by. Brug dette naar brugeren spoerger om vejret.",
8        "input_schema": {
9            "type": "object",
10            "properties": {
11                "city": {
12                    "type": "string",
13                    "description": "Byens navn, f.eks. 'Kobenhavn'"
14                },
15                "unit": {
16                    "type": "string",
17                    "enum": ["celsius", "fahrenheit"],
18                    "description": "Temperatur enhed"
19                }
20            },
21            "required": ["city"]
22        }
23    },
24    {
25        "name": "search_database",
26        "description": "Soeg i produktdatabasen efter produkter",
27        "input_schema": {
28            "type": "object",
29            "properties": {
30                "query": {"type": "string", "description": "Soegeord"},
31                "max_results": {"type": "integer", "description": "Max antal resultater"}
32            },
33            "required": ["query"]
34        }
35    }
36]
37
38# Your actual functions
39def get_weather(city: str, unit: str = "celsius") -> dict:
40    # In reality, call a weather API
41    return {"city": city, "temp": 18, "unit": unit, "condition": "Overskyet"}
42
43def search_database(query: str, max_results: int = 5) -> list:
44    # In reality, query your database
45    return [{"name": f"Produkt {i}", "price": 100 + i*10} for i in range(max_results)]
46
47# Process tool calls
48def process_tool_call(tool_name: str, tool_input: dict) -> str:
49    if tool_name == "get_weather":
50        result = get_weather(**tool_input)
51    elif tool_name == "search_database":
52        result = search_database(**tool_input)
53    else:
54        result = {"error": f"Unknown tool: {tool_name}"}
55    return json.dumps(result)
56
57# Make request with tools
58response = client.messages.create(
59    model="claude-sonnet-4-20250514",
60    max_tokens=1024,
61    tools=tools,
62    messages=[{"role": "user", "content": "Hvordan er vejret i Aarhus?"}]
63)
64
65# Handle tool use
66if response.stop_reason == "tool_use":
67    # Find the tool use block
68    tool_use = next(block for block in response.content if block.type == "tool_use")
69
70    # Execute the tool
71    tool_result = process_tool_call(tool_use.name, tool_use.input)
72
73    # Send result back to Claude
74    final_response = client.messages.create(
75        model="claude-sonnet-4-20250514",
76        max_tokens=1024,
77        tools=tools,
78        messages=[
79            {"role": "user", "content": "Hvordan er vejret i Aarhus?"},
80            {"role": "assistant", "content": response.content},
81            {
82                "role": "user",
83                "content": [{
84                    "type": "tool_result",
85                    "tool_use_id": tool_use.id,
86                    "content": tool_result
87                }]
88            }
89        ]
90    )
91    print(final_response.content[0].text)

1import base64
2import httpx
3
4# From local file
5def encode_image(image_path: str) -> str:
6    with open(image_path, "rb") as f:
7        return base64.standard_b64encode(f.read()).decode("utf-8")
8
9# From URL
10def fetch_image_base64(url: str) -> str:
11    response = httpx.get(url)
12    return base64.standard_b64encode(response.content).decode("utf-8")
13
14# Analyze local image
15message = client.messages.create(
16    model="claude-sonnet-4-20250514",
17    max_tokens=1024,
18    messages=[
19        {
20            "role": "user",
21            "content": [
22                {
23                    "type": "image",
24                    "source": {
25                        "type": "base64",
26                        "media_type": "image/jpeg",
27                        "data": encode_image("diagram.jpg")
28                    }
29                },
30                {
31                    "type": "text",
32                    "text": "Forklar hvad dette arkitektur-diagram viser. List komponenterne."
33                }
34            ]
35        }
36    ]
37)
38
39# Multiple images
40message = client.messages.create(
41    model="claude-sonnet-4-20250514",
42    max_tokens=1024,
43    messages=[
44        {
45            "role": "user",
46            "content": [
47                {"type": "image", "source": {"type": "base64", "media_type": "image/png", "data": img1_b64}},
48                {"type": "image", "source": {"type": "base64", "media_type": "image/png", "data": img2_b64}},
49                {"type": "text", "text": "Sammenlign disse to designs. Hvad er forskellene?"}
50            ]
51        }
52    ]
53)

1from anthropic import (
2    Anthropic,
3    APIError,
4    RateLimitError,
5    APIConnectionError,
6    AuthenticationError
7)
8import time
9from functools import wraps
10
11client = Anthropic()
12
13def retry_with_backoff(max_retries: int = 3, base_delay: float = 1.0):
14    def decorator(func):
15        @wraps(func)
16        def wrapper(*args, **kwargs):
17            last_exception = None
18            for attempt in range(max_retries):
19                try:
20                    return func(*args, **kwargs)
21                except RateLimitError as e:
22                    last_exception = e
23                    # Respect retry-after header if present
24                    delay = float(e.response.headers.get("retry-after", base_delay * (2 ** attempt)))
25                    print(f"Rate limited. Waiting {delay:.1f}s...")
26                    time.sleep(delay)
27                except APIConnectionError as e:
28                    last_exception = e
29                    delay = base_delay * (2 ** attempt)
30                    print(f"Connection error. Retrying in {delay:.1f}s...")
31                    time.sleep(delay)
32                except AuthenticationError:
33                    # Don't retry auth errors
34                    raise
35                except APIError as e:
36                    if e.status_code >= 500:
37                        # Server error, worth retrying
38                        last_exception = e
39                        time.sleep(base_delay * (2 ** attempt))
40                    else:
41                        raise
42            raise last_exception
43        return wrapper
44    return decorator
45
46@retry_with_backoff(max_retries=3)
47def call_claude(messages: list, **kwargs):
48    return client.messages.create(
49        model="claude-sonnet-4-20250514",
50        messages=messages,
51        **kwargs
52    )

1# 1. Use the right model for the task
2def get_model_for_task(task_complexity: str) -> str:
3    """Choose model based on task complexity."""
4    if task_complexity == "simple":
5        return "claude-haiku-3.5-20250101"  # Cheapest
6    elif task_complexity == "moderate":
7        return "claude-sonnet-4-20250514"   # Best value
8    else:
9        return "claude-opus-4-20250514"     # Most capable
10
11# 2. Limit output tokens
12response = client.messages.create(
13    model="claude-sonnet-4-20250514",
14    max_tokens=500,  # Don't use more than needed
15    messages=[...]
16)
17
18# 3. Use caching for repeated prompts
19from functools import lru_cache
20import hashlib
21
22@lru_cache(maxsize=1000)
23def cached_claude_call(prompt_hash: str, prompt: str) -> str:
24    response = client.messages.create(
25        model="claude-sonnet-4-20250514",
26        max_tokens=1024,
27        messages=[{"role": "user", "content": prompt}]
28    )
29    return response.content[0].text
30
31def call_with_cache(prompt: str) -> str:
32    prompt_hash = hashlib.md5(prompt.encode()).hexdigest()
33    return cached_claude_call(prompt_hash, prompt)
34
35# 4. Track costs
36def estimate_cost(response) -> float:
37    """Estimate cost in USD for a response."""
38    # Sonnet 4 pricing
39    input_cost = response.usage.input_tokens * 3 / 1_000_000
40    output_cost = response.usage.output_tokens * 15 / 1_000_000
41    return input_cost + output_cost