{"id":4525,"library":"eccodes","title":"eccodes Python Interface","description":"The eccodes library provides a Python interface to the ECMWF ecCodes GRIB and BUFR decoder/encoder. It allows users to read, write, and manipulate GRIB and BUFR meteorological data files, providing both a low-level API mapping directly to the C library and a higher-level object-oriented interface. It is actively maintained by ECMWF with frequent releases, typically every 1-2 months, mirroring the underlying ecCodes C library.","status":"active","version":"2.46.0","language":"python","source_language":"en","source_url":"https://github.com/ecmwf/eccodes-python","tags":["GRIB","BUFR","meteorology","data processing","ECMWF","weather"],"install":[{"cmd":"pip install eccodes","lang":"bash","label":"Install with pip"}],"dependencies":[],"imports":[{"note":"General import for accessing all eccodes functionalities.","symbol":"eccodes","correct":"import eccodes"},{"note":"Import for low-level C API functions, e.g., codes.codes_open_file, codes.codes_get.","symbol":"codes","correct":"from eccodes import codes"},{"note":"High-level context manager for reading GRIB files, providing an iterator over GribMessage objects.","symbol":"GribFile","correct":"from eccodes import GribFile"},{"note":"High-level object representing a single GRIB message, allowing dictionary-like access to keys.","symbol":"GribMessage","correct":"from eccodes import GribMessage"},{"note":"High-level context manager for reading BUFR files, similar to GribFile.","symbol":"BufrFile","correct":"from eccodes import BufrFile"},{"note":"High-level object representing a single BUFR message, allowing dictionary-like access to keys.","symbol":"BufrMessage","correct":"from eccodes import BufrMessage"}],"quickstart":{"code":"import eccodes\nimport os\n\n# --- Quickstart setup: Ensure a GRIB file exists for demonstration ---\n# In a real scenario, you would point to your actual GRIB file.\ngrib_filepath = \"quickstart_sample.grib\"\n\nif not os.path.exists(grib_filepath):\n    print(f\"Creating a dummy GRIB file '{grib_filepath}' for quickstart.\")\n    try:\n        # Create a basic GRIB message from a sample.\n        # This requires the eccodes sample data to be accessible.\n        # If ECCODES_SAMPLES_PATH is not set, this might fail.\n        gid = eccodes.codes_grib_new_from_samples(\"GRIB2\")\n        eccodes.codes_set(gid, \"discipline\", 0) # Meteorology\n        eccodes.codes_set(gid, \"parameterCategory\", 0) # Temperature\n        eccodes.codes_set(gid, \"parameterNumber\", 0) # Temperature (K)\n        eccodes.codes_set_array(gid, \"values\", [273.15, 274.15, 275.15]) # Dummy data\n        with open(grib_filepath, 'wb') as f:\n            eccodes.codes_write(gid, f)\n        eccodes.codes_release(gid)\n        print(f\"Successfully created a basic GRIB file: {grib_filepath}\")\n    except eccodes.CodesInternalError as e:\n        print(f\"Warning: Could not create a valid GRIB sample using eccodes ({e}).\")\n        print(\"Falling back to an empty dummy file. Quickstart may not show full functionality.\")\n        with open(grib_filepath, 'w') as f:\n            f.write(\"DUMMY_FILE_CONTENT_NOT_GRIB\")\n    except Exception as e:\n        print(f\"An unexpected error occurred during GRIB sample creation: {e}\")\n        with open(grib_filepath, 'w') as f:\n            f.write(\"DUMMY_FILE_CONTENT_NOT_GRIB\")\n# --- End of Quickstart setup ---\n\n# Main Quickstart logic: Reading GRIB messages\ntry:\n    message_count = 0\n    with eccodes.GribFile(grib_filepath) as gf:\n        print(f\"\\nOpened GRIB file: {grib_filepath}\")\n        for i, msg in enumerate(gf):\n            message_count += 1\n            print(f\"  Processing Message {i+1}:\")\n            try:\n                # Access common keys using the high-level interface\n                centre = msg.get(\"centre\", \"N/A\")\n                param = msg.get(\"shortName\", \"N/A\")\n                level = msg.get(\"level\", \"N/A\")\n                date = msg.get(\"date\", \"N/A\")\n                time = msg.get(\"time\", \"N/A\")\n                print(f\"    Centre: {centre}, Parameter: {param}, Level: {level}, Date: {date}, Time: {time}\")\n\n                # Access values (can be a large array). Avoid printing all.\n                values = msg.get(\"values\", [])\n                if values:\n                    print(f\"    First 5 values: {values[:min(5, len(values))]}\")\n                else:\n                    print(\"    No values found or dummy file used.\")\n\n            except eccodes.KeyError as e:\n                print(f\"    Warning: Key not found in message: {e}\")\n            except Exception as e:\n                print(f\"    An error occurred while processing message: {e}\")\n\n            if message_count >= 1: # Process only the first message for brevity\n                break\n\n    if message_count == 0:\n        print(f\"No GRIB messages found in {grib_filepath}. (Might be a dummy file or empty).\")\n\nexcept eccodes.WrongElementException as e:\n    print(f\"\\nError: '{grib_filepath}' is not a valid GRIB file or corrupted. Details: {e}\")\nexcept FileNotFoundError:\n    print(f\"\\nError: GRIB file '{grib_filepath}' not found.\")\nexcept Exception as e:\n    print(f\"\\nAn unexpected error occurred during GRIB file processing: {e}\")\nfinally:\n    # Clean up the dummy file\n    if os.path.exists(grib_filepath) and grib_filepath == \"quickstart_sample.grib\":\n        os.remove(grib_filepath)\n        print(f\"Cleaned up dummy file: {grib_filepath}\")","lang":"python","description":"This quickstart demonstrates how to open a GRIB file, iterate through its messages using the high-level `GribFile` context manager, and access common keys from individual `GribMessage` objects. It includes robust error handling and setup to create a dummy GRIB file if a real one isn't provided, ensuring the example is runnable out-of-the-box."},"warnings":[{"fix":"Prefer using the high-level `GribFile` and `BufrFile` context managers (e.g., `with eccodes.GribFile(...) as gf:`) which handle resource cleanup automatically. If using the low-level API, ensure `codes_release()` and `codes_close_file()` are called in a `finally` block or context manager.","message":"Resource management: When using the low-level `codes` API (e.g., `codes_grib_new_from_file`), it's crucial to explicitly call `codes_release(handle)` and `codes_close_file(file_handle)` to prevent memory leaks and file descriptor exhaustion. Failure to do so is a common source of instability in long-running applications.","severity":"gotcha","affected_versions":"All versions"},{"fix":"Choose one API style and stick to it for clarity and consistency. The high-level API is generally recommended for new development due to its ease of use and automatic resource management. Only use the low-level API when specific C-level functionality is required.","message":"Mixing high-level and low-level APIs: The library offers both a direct Python binding to the C API (`eccodes.codes`) and a higher-level, more Pythonic interface (`GribFile`, `BufrFile`, `GribMessage`, `BufrMessage`). Mixing these paradigms within the same code path, especially regarding message handles, can lead to unexpected behavior or resource management issues.","severity":"gotcha","affected_versions":"All versions"},{"fix":"Carefully review the release notes for BUFR-related changes when upgrading. Thoroughly test code interacting with the high-level BUFR API after any version update. Consult the official ECMWF eccodes-python documentation for the latest BUFR API usage patterns.","message":"High-level BUFR API changes: The high-level BUFR interface has seen significant development and fixes across recent versions (e.g., 2.41.0, 2.44.0, 2.46.0). This means methods like `set` and `get` for BUFR data keys might have changed behavior or arguments between minor versions.","severity":"breaking","affected_versions":"2.41.0 and later, particularly for BUFR users."},{"fix":"For most users, relying on the pre-built wheels provided on PyPI is the simplest solution. If building from source is necessary, ensure `ecCodes` is installed on your system (e.g., via `conda install -c conda-forge eccodes-cpp` or your system package manager) and that its development files are discoverable during the `pip install` process.","message":"External C library dependency for custom builds: While `pip install eccodes` typically provides pre-built wheels that bundle the underlying `ecCodes` C library, building from source or using the `--no-binary eccodes` option requires a system-level installation of the `ecCodes` C library and its development headers. Failure to meet these dependencies will result in compilation errors.","severity":"gotcha","affected_versions":"All versions when building from source or using `--no-binary`."}],"env_vars":null,"search_vec":"'-2':67 '1':66 'activ':57 'allow':20 'api':39 'bufr':17,29,76 'c':44,73 'data':31,78 'decoder/encoder':18 'direct':41 'eccod':1,5,14,72 'ecmwf':13,60,80 'everi':65 'file':32 'frequent':62 'grib':15,27,75 'higher':49 'higher-level':48 'interfac':3,10,54 'level':38,50 'librari':6,45,74 'low':37 'low-level':36 'maintain':58 'manipul':26 'map':40 'meteorolog':30,77 'mirror':69 'month':68 'object':52 'object-ori':51 'orient':53 'process':79 'provid':7,33 'python':2,9 'read':23 'releas':63 'typic':64 'under':71 'user':21 'weather':81 'write':24","created_at":"2026-04-12T13:56:22.920977+00:00","updated_at":"2026-04-16T14:45:59.640028+00:00","problems":[{"fix":"Ensure the ecCodes C library is installed. On Linux/macOS, if installed via `conda`, use `conda install -c conda-forge eccodes`. If using `pip` from version 2.37.0 onwards, the binary library is often bundled, but issues can still arise. For debugging, set the environment variable `ECCODES_PYTHON_TRACE_LIB_SEARCH=1` before importing `eccodes` to see where it's looking. If installed separately, ensure `LD_LIBRARY_PATH` (Linux) or `DYLD_LIBRARY_PATH` (macOS) points to the directory containing the ecCodes shared library.","cause":"The Python `eccodes` package, which provides bindings, cannot locate the underlying ECMWF ecCodes C library on your system. This often happens if the C library is not installed, not in a standard path, or if environment variables are not correctly set.","error":"RuntimeError: Cannot find the ecCodes library!"},{"fix":"Verify the exact key name and its applicability to your GRIB/BUFR message using tools like `grib_ls` or `grib_dump` (from the ecCodes command-line tools) or by iterating through keys in the `eccodes` Python interface. Ensure correct casing and spelling. For example:\n```python\nimport eccodes\n\nwith open('your_grib_file.grib', 'rb') as f:\n    while True:\n        msgid = eccodes.codes_grib_new_from_file(f)\n        if msgid is None:\n            break\n        # Correct key name, e.g., 'paramId'\n        try:\n            param_id = eccodes.codes_get_long(msgid, 'paramId')\n            print(f\"paramId: {param_id}\")\n        except eccodes.CodesInternalError as e:\n            print(f\"Error accessing key: {e}\")\n        eccodes.codes_release(msgid)\n```","cause":"You are attempting to access or set a GRIB/BUFR key that does not exist in the message, is misspelled, or is not applicable to the specific GRIB/BUFR edition or template of the message being processed.","error":"eccodes.CodesInternalError: Key/value not found"},{"fix":"Ensure the `eccodes` library and its definitions are correctly installed. If using `conda`, install both `eccodes` and `cfgrib` (which often handles definition paths). If installing from source or encountering this error, set the `ECCODES_DEFINITION_PATH` environment variable to the directory where the `definitions` and `samples` subdirectories of ecCodes are located. You can also run `python -m eccodes selfcheck` to diagnose the issue.","cause":"The `eccodes` library cannot find its definition files, which are crucial for decoding and encoding GRIB and BUFR messages. This usually points to an incorrect installation or an improperly set `ECCODES_DEFINITION_PATH` environment variable.","error":"ECCODES ERROR : Unable to find boot.def. Context path=/path/to/eccodes/definitions."},{"fix":"Use the type-specific `codes_get_*` and `codes_set_*` functions provided by the `eccodes` module. For example, to get a long integer key, use `eccodes.codes_get_long(msgid, 'paramId')`, and for a string, use `eccodes.codes_get_string(msgid, 'shortName')`. Similarly for setting values, use `eccodes.codes_set_long()` or `eccodes.codes_set_string()`.","cause":"The `eccodes` Python interface closely mirrors the C API, which uses specific functions for getting/setting different data types (e.g., `codes_get_long`, `codes_get_string`, `codes_set_double`). There isn't a generic `eccodes.get()` or `eccodes.set()` method directly on the module or handle object in the C-like API.","error":"AttributeError: module 'eccodes' has no attribute 'get'"}],"ecosystem":"pypi","meta_description":null,"install_score":null,"quickstart_score":null,"quickstart_tag":null,"pypi_latest":"2.48.0","cli_name":"eccodes","cli_version":"sh: 1: eccodes: not found","type":"library","homepage":"https://confluence.ecmwf.int/display/ECC","github":"https://github.com/ecmwf/eccodes-python","docs":null,"changelog":null,"pypi":"https://pypi.org/project/eccodes/","npm":null,"openapi_spec":null,"status_page":null,"smithery":null,"categories":["data","serialization"],"base_url":null,"auth_type":null,"provenance":{"verified_status":"passing","verified_at":"2026-06-28","last_verified":"2026-08-30","next_check":"2026-07-28","install_tag":null}}