用matlab读取edf格式的脑电时，其数值是脑电的幅值吗？

wanra

用matlab读取edf格式的脑电时，matlab上的读数是脑电的幅值吗？

ChaChing

个人水平专业有限, 不知edf格式是什么? :@L

shenlinayezi

冒昧问你一下你是怎么用matlab读取edf文件的？

ChaChing

其实只要知道资料档案的格式, 使用fread就一定可以读!
帮搜索下, 不过个人没edf的资料, 没试过
试过的人再说说是否可用
From http://www.mathworks.com/matlabcentral/fileexchange/31900-edfread

1. function [hdr, record] = edfRead(fname, varargin)
   
2. % Read European Data Format file into MATLAB
   
3. %
   
4. % [hdr, record] = edfRead(fname)
   
5. %         Reads data from ALL RECORDS of file fname ('*.edf'). Header
   
6. %         information is returned in structure hdr, and the signals
   
7. %         (waveforms) are returned in structure record, with waveforms
   
8. %         associated with the records returned as fields titled 'data' of
   
9. %         structure record.
   
10. %
    
11. % [...] = edfRead(fname, 'assignToVariables', assignToVariables)
    
12. %         Triggers writing of individual output variables, as defined by
    
13. %         field 'labels', into the caller workspace.
    
14. %
    
15. % FORMAT SPEC: Source: http://www.edfplus.info/specs/edf.html SEE ALSO:
    
16. % http://www.dpmi.tu-graz.ac.at/~schloegl/matlab/eeg/edf_spec.htm
    
17. %
    
18. % The first 256 bytes of the header record specify the version number of
    
19. % this format, local patient and recording identification, time information
    
20. % about the recording, the number of data records and finally the number of
    
21. % signals (ns) in each data record. Then for each signal another 256 bytes
    
22. % follow in the header record, each specifying the type of signal (e.g.
    
23. % EEG, body temperature, etc.), amplitude calibration and the number of
    
24. % samples in each data record (from which the sampling frequency can be
    
25. % derived since the duration of a data record is also known). In this way,
    
26. % the format allows for different gains and sampling frequencies for each
    
27. % signal. The header record contains 256 + (ns * 256) bytes.
    
28. %
    
29. % Following the header record, each of the subsequent data records contains
    
30. % 'duration' seconds of 'ns' signals, with each signal being represented by
    
31. % the specified (in the header) number of samples. In order to reduce data
    
32. % size and adapt to commonly used software for acquisition, processing and
    
33. % graphical display of polygraphic signals, each sample value is
    
34. % represented as a 2-byte integer in 2's complement format. Figure 1 shows
    
35. % the detailed format of each data record.
    
36. %
    
37. % DATA SOURCE: Signals of various types (including the sample signal used
    
38. % below) are available from PHYSIONET: http://www.physionet.org/
    
39. %
    
40. %
    
41. % % EXAMPLE 1:
    
42. % % Read all waveforms/data associated with file 'ecgca998.edf':
    
43. %
    
44. % [header, recorddata] = edfRead('ecgca998.edf');
    
45. %
    
46. % % EXAMPLE 2:
    
47. % % Read records 3 and 5, associated with file 'ecgca998.edf':
    
48. %
    
49. % header = edfRead('ecgca998.edf','AssignToVariables',true);
    
50. % % Header file specifies data labels 'label_1'...'label_n'; these are
    
51. % % created as variables in the caller workspace.
    
52. %
    
53. % Coded 8/27/09 by Brett Shoelson, PhD
    
54. % brett.shoelson@mathworks.com
    
55. % Copyright 2009 - 2012 MathWorks, Inc.
    
56. 
    
57. % HEADER RECORD
    
58. % 8 ascii : version of this data format (0)
    
59. % 80 ascii : local patient identification
    
60. % 80 ascii : local recording identification
    
61. % 8 ascii : startdate of recording (dd.mm.yy)
    
62. % 8 ascii : starttime of recording (hh.mm.ss)
    
63. % 8 ascii : number of bytes in header record
    
64. % 44 ascii : reserved
    
65. % 8 ascii : number of data records (-1 if unknown)
    
66. % 8 ascii : duration of a data record, in seconds
    
67. % 4 ascii : number of signals (ns) in data record
    
68. % ns * 16 ascii : ns * label (e.g. EEG FpzCz or Body temp)
    
69. % ns * 80 ascii : ns * transducer type (e.g. AgAgCl electrode)
    
70. % ns * 8 ascii : ns * physical dimension (e.g. uV or degreeC)
    
71. % ns * 8 ascii : ns * physical minimum (e.g. -500 or 34)
    
72. % ns * 8 ascii : ns * physical maximum (e.g. 500 or 40)
    
73. % ns * 8 ascii : ns * digital minimum (e.g. -2048)
    
74. % ns * 8 ascii : ns * digital maximum (e.g. 2047)
    
75. % ns * 80 ascii : ns * prefiltering (e.g. HP:0.1Hz LP:75Hz)
    
76. % ns * 8 ascii : ns * nr of samples in each data record
    
77. % ns * 32 ascii : ns * reserved
    
78. 
    
79. % DATA RECORD
    
80. % nr of samples[1] * integer : first signal in the data record
    
81. % nr of samples[2] * integer : second signal
    
82. % ..
    
83. % ..
    
84. % nr of samples[ns] * integer : last signal
    
85. 
    
86. if nargin > 3
    
87.     error('EDFREAD: Too many input arguments.');
    
88. end
    
89. 
    
90. if ~nargin
    
91.     error('EDFREAD: Requires at least one input argument (filename to read).');
    
92. end
    
93. 
    
94. if nargin == 1
    
95.     assignToVariables = false;
    
96. end
    
97. 
    
98. [fid,msg] = fopen(fname,'r');
    
99. if fid == -1
    
100.     error(msg)
     
101. end
     
102. 
     
103. assignToVariables = false; %Default
     
104. for ii = 1:2:numel(varargin)
     
105.     switch lower(varargin{ii})
     
106.         case 'assigntovariables'
     
107.             assignToVariables = varargin{ii+1};
     
108.     end
     
109. end
     
110. 
     
111. % HEADER
     
112. hdr.ver        = str2double(char(fread(fid,8)'));
     
113. hdr.patientID  = fread(fid,80,'*char')';
     
114. hdr.recordID   = fread(fid,80,'*char')';
     
115. hdr.startdate  = fread(fid,8,'*char')';% (dd.mm.yy)
     
116. % hdr.startdate  = datestr(datenum(fread(fid,8,'*char')','dd.mm.yy'), 29); %'yyyy-mm-dd' (ISO 8601)
     
117. hdr.starttime  = fread(fid,8,'*char')';% (hh.mm.ss)
     
118. % hdr.starttime  = datestr(datenum(fread(fid,8,'*char')','hh.mm.ss'), 13); %'HH:MM:SS' (ISO 8601)
     
119. hdr.bytes      = str2double(fread(fid,8,'*char')');
     
120. reserved       = fread(fid,44);
     
121. hdr.records    = str2double(fread(fid,8,'*char')');
     
122. hdr.duration   = str2double(fread(fid,8,'*char')');
     
123. % Number of signals
     
124. hdr.ns    = str2double(fread(fid,4,'*char')');
     
125. for ii = 1:hdr.ns
     
126.     hdr.label{ii} = fread(fid,16,'*char')';
     
127. end
     
128. for ii = 1:hdr.ns
     
129.     hdr.transducer{ii} = fread(fid,80,'*char')';
     
130. end
     
131. % Physical dimension
     
132. for ii = 1:hdr.ns
     
133.     hdr.units{ii} = fread(fid,8,'*char')';
     
134. end
     
135. % Physical minimum
     
136. for ii = 1:hdr.ns
     
137.     hdr.physicalMin(ii) = str2double(fread(fid,8,'*char')');
     
138. end
     
139. % Physical maximum
     
140. for ii = 1:hdr.ns
     
141.     hdr.physicalMax(ii) = str2double(fread(fid,8,'*char')');
     
142. end
     
143. % Digital minimum
     
144. for ii = 1:hdr.ns
     
145.     hdr.digitalMin(ii) = str2double(fread(fid,8,'*char')');
     
146. end
     
147. % Digital maximum
     
148. for ii = 1:hdr.ns
     
149.     hdr.digitalMax(ii) = str2double(fread(fid,8,'*char')');
     
150. end
     
151. for ii = 1:hdr.ns
     
152.     hdr.prefilter{ii} = fread(fid,80,'*char')';
     
153. end
     
154. for ii = 1:hdr.ns
     
155.     hdr.samples(ii) = str2double(fread(fid,8,'*char')');
     
156. end
     
157. for ii = 1:hdr.ns
     
158.     reserved    = fread(fid,32,'*char')';
     
159. end
     
160. hdr.label = deblank(hdr.label);
     
161. hdr.units = deblank(hdr.units);
     
162. 
     
163. 
     
164. if nargout > 1 || assignToVariables
     
165.     % Scale data (linear scaling)
     
166.     scalefac = (hdr.physicalMax - hdr.physicalMin)./(hdr.digitalMax - hdr.digitalMin);
     
167.     dc = hdr.physicalMax - scalefac .* hdr.digitalMax;
     
168.    
     
169.     % RECORD DATA REQUESTED
     
170.     tmpdata = struct;
     
171.     for recnum = 1:hdr.records
     
172.         for ii = 1:hdr.ns
     
173.             % Use a cell array for DATA because number of samples may vary
     
174.             % from sample to sample
     
175.             tmpdata(recnum).data{ii} = fread(fid,hdr.samples(ii),'int16') * scalefac(ii) + dc(ii);
     
176.         end
     
177.     end
     
178.     record = zeros(hdr.ns, hdr.samples(1)*hdr.records);
     
179.    
     
180.     for ii = 1:numel(hdr.label)
     
181.         ctr = 1;
     
182.         for jj = 1:hdr.records
     
183.             try
     
184.                 record(ii, ctr : ctr + hdr.samples - 1) = tmpdata(jj).data{ii};
     
185.             end
     
186.             ctr = ctr + hdr.samples;
     
187.         end
     
188.     end
     
189.    
     
190.     if assignToVariables
     
191.         for ii = 1:numel(hdr.label)
     
192.             try
     
193.                 eval(['assignin(''caller'',''',hdr.label{ii},''',record(ii,:))'])
     
194.             end
     
195.         end
     
196.     end
     
197. end
     
198. fclose(fid);

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