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1# -*- coding: utf-8 -*- 

2""" 

3=============================== 

4Transfer Functions Metadata 

5=============================== 

6 

7This module provides a central container (TF) for magnetotelluric transfer functions, 

8which represent the electromagnetic response of the Earth. Transfer functions relate 

9the measured magnetic and electric fields and are fundamental to magnetotelluric 

10interpretation. 

11 

12The primary goal is to create a unified transfer function object that can read from 

13and write to various industry-standard file formats through the io module, enabling 

14seamless data interchange and analysis across different MT software packages. 

15 

16MetadataBase Objects 

17-------------------- 

18* TF - Main transfer function container with impedance, tipper, and associated metadata 

19* Station - Station-level metadata specific to transfer function processing 

20* TransferFunction - Core transfer function metadata (impedance, tipper, processing info) 

21* StatisticalEstimate - Statistical quality metrics and error estimates for transfer functions 

22 

23Supported File Formats (io module) 

24---------------------------------- 

25The io module supports reading and writing the following transfer function formats: 

26 

27* **EDI** - SEG (Society of Exploration Geophysicists) EDI format, the most common 

28 MT interchange format 

29* **EMTFXML** - EMTF (Electromagnetic Transfer Function) XML format with extended 

30 metadata support 

31* **ZMM** - BIRRP processing output format (impedance and vertical field data) 

32* **JFile** - EMTF/BIRRP .j format for transfer function coefficients 

33* **ZongeMTAvg** - Zonge International averaged MT data format 

34 

35Channel Nomenclature 

36-------------------- 

37The module supports multiple channel naming conventions from different acquisition 

38systems (default, LEMI, Phoenix, Musgraves, NIMS), with automatic mapping between 

39standard channel names (hx, hy, hz, ex, ey) and system-specific labels. 

40 

41Usage 

42----- 

43The TF object serves as a central repository that: 

44- Stores transfer functions in an xarray.Dataset for efficient computation 

45- Provides helper methods to access impedance, tipper, errors, and covariances 

46- Reads/writes to multiple file formats transparently 

47- Maintains full metadata provenance and processing history 

48- Supports coordinate rotations and datum transformations 

49 

50""" 

51 

52# Define allowed sets of channel labellings 

53STANDARD_INPUT_CHANNELS = [ 

54 "hx", 

55 "hy", 

56] 

57STANDARD_OUTPUT_CHANNELS = [ 

58 "ex", 

59 "ey", 

60 "hz", 

61] 

62 

63# channel nomenclature mappings 

64CHANNEL_MAPS = { 

65 "default": {"hx": "hx", "hy": "hy", "hz": "hz", "ex": "ex", "ey": "ey"}, 

66 "lemi12": {"hx": "bx", "hy": "by", "hz": "bz", "ex": "e1", "ey": "e2"}, 

67 "lemi34": {"hx": "bx", "hy": "by", "hz": "bz", "ex": "e3", "ey": "e4"}, 

68 "phoenix123": {"hx": "h1", "hy": "h2", "hz": "h3", "ex": "e1", "ey": "e2"}, 

69 "musgraves": {"hx": "bx", "hy": "by", "hz": "bz", "ex": "ex", "ey": "ey"}, 

70} 

71CHANNEL_MAPS["nims"] = CHANNEL_MAPS[ 

72 "default" 

73] # Alias NIMS system to use same config as default 

74 

75 

76def get_allowed_channel_names(standard_names): 

77 """ 

78 :param standard_names: one of STANDARD_INPUT_NAMES, or STANDARD_OUTPUT_NAMES 

79 :type standard_names: list 

80 :return: allowed_names: list of channel names that are supported 

81 :rtype: list 

82 """ 

83 allowed_names = [] 

84 for ch in standard_names: 

85 for _, channel_map in CHANNEL_MAPS.items(): 

86 allowed_names.append(channel_map[ch]) 

87 allowed_names = list(set(allowed_names)) 

88 return allowed_names 

89 

90 

91ALLOWED_INPUT_CHANNELS = get_allowed_channel_names(STANDARD_INPUT_CHANNELS) 

92ALLOWED_OUTPUT_CHANNELS = get_allowed_channel_names(STANDARD_OUTPUT_CHANNELS) 

93 

94from .core import TF 

95 

96 

97__all__ = ["TF"]