matlab dbf读取

function [dbfData, dbfFieldNames] = dbfread(filename, records2read, requestedFieldNames) %DBFREAD Read the specified records and fields from a DBF file. % % [DATA, NAMES] = DBFREAD(FILE) reads numeric, float, character and date % data and field names from a DBF file, FILE. % % [DATA, NAMES] = DBFREAD(FILE, RECORDS2READ) reads only the record % numbers specified in RECORDS2READ, a scalar or vector. % % [DATA, NAMES] = DBFREAD(FILE, RECORDS2READ, REQUESTEDFIELDNAMES) reads % the data from the fields, REQUESTEDFIELDNAMES, for the specified % records. REQUESTEDFIELDNAMES must be a cell array. The fields in the % output will follow the order given in REQUESTEDFIELDNAMES. % % Examples: % % % Get all records and a list of the field names from a DBF file. % [DATA,NAMES] = dbfread('c:\matlab\work\mydbf') % % % Get data from records 3:5 and 10 from a DBF file. % DATA = dbfread('c:\matlab\work\mydbf',[3:5,10]) % % % Get data from records 1:10 for three of the fields in a DBF file. % DATA = dbfread('c:\matlab\work\mydbf',1:10,{'FIELD1' 'FIELD3' 'FIELD5'}) % % See also XLSREAD, DLMREAD, DLMWRITE, LOAD, FILEFORMATS, TEXTSCAN. % Copyright 2008 The MathWorks, Inc. % $Revision: 1.0 $ $Date: 2008/04/18 05:58:17 $ [pathstr,name,ext] = fileparts(filename); dbfFileId = fopen([pathstr filesep name '.dbf'],'r','ieee-le'); if (dbfFileId == -1) dbfFileId = fopen([pathstr filesep name '.DBF'],'r','ieee-le'); end if (dbfFileId == -1) eid = sprintf('MATLAB:%s:missingDBF', mfilename); msg = sprintf('Failed to open file %s.dbf or file %s.DBF.',... name, name); error(eid,'%s',msg) end info = dbfinfo(dbfFileId); if ~exist('requestedFieldNames','var') dbfFieldNames = {info.FieldInfo.Name}; requestedFieldNames = dbfFieldNames; else dbfFieldNames = (info.FieldInfo(matchFieldNames(info,requestedFieldNames)).Name); end fields2read = matchFieldNames(info,requestedFieldNames); % The first byte in each record is a deletion indicator lengthOfDeletionIndicator = 1; if ~exist('records2read','var') records2read = (1:info.NumRecords); elseif max(records2read) > info.NumRecords eid = sprintf('MATLAB:%s:invalidRecordNumber', mfilename); msg = sprintf('Record number %d does not exist, please select from the range 1:%d.',... max(records2read), info.NumRecords); error(eid,'%s',msg) end % Loop over the requested fields, reading in the data dbfData = cell(numel(records2read),numel(fields2read)); for k = 1:numel(fields2read), n = fields2read(k); fieldOffset = info.HeaderLength ... + sum([info.FieldInfo(1:(n-1)).Length]) ... + lengthOfDeletionIndicator; fseek(dbfFileId,fieldOffset,'bof'); formatString = sprintf('%d*uint8=>char',info.FieldInfo(n).Length); skip = info.RecordLength - info.FieldInfo(n).Length; data = fread(dbfFileId,[info.FieldInfo(n).Length info.NumRecords],formatString,skip); dbfData(:,k) = info.FieldInfo(n).ConvFunc(data(:,records2read)'); end fclose(dbfFileId); %-------------------------------------------------------------------------- function fields2read = matchFieldNames(info, requestedFieldNames) % Determine which fields to read. allFieldNames = {info.FieldInfo.Name}; if isempty(requestedFieldNames) if ~iscell(requestedFieldNames) % Default case: User omitted the parameter, return all fields. fields2read = 1:info.NumFields; else % User supplied '{}', skip all fields. fields2read = []; end else % Match up field names to see which to return. fields2read = []; for k = 1:numel(requestedFieldNames) index = strmatch(requestedFieldNames{k},allFieldNames,'exact'); if isempty(index) wid = sprintf('MATLAB:%s:nonexistentDBFName',mfilename); wrn = sprintf('DBF name ''%s'' %s\n%s',requestedFieldNames{k},... 'doesn''t match an existing DBF name.',... ' It will be ignored.'); warning(wid,wrn) end for l = 1:numel(index) % Take them all in case of duplicate names. fields2read(end+1) = index(l); end end end %-------------------------------------------------------------------------- function info = dbfinfo(fid) %DBFINFO Read header information from DBF file. % FID File identifier for an open DBF file. % INFO is a structure with the following fields: % Filename Char array containing the name of the file that was read % DBFVersion Number specifying the file format version % FileModDate A string containing the modification date of the file % NumRecords A number specifying the number of records in the table % NumFields A number specifying the number of fields in the table % FieldInfo A 1-by-numFields structure array with fields: % Name A string containing the field name % Type A string containing the field type % ConvFunc A function handle to convert from DBF to MATLAB type % Length A number of bytes in the field % HeaderLength A number specifying length of the file header in bytes % RecordLength A number specifying length of each record in bytes % Copyright 1996-2005 The MathWorks, Inc. % $Revision: 1.1.10.4 $ $Date: 2005/11/15 01:07:13 $ [version, date, numRecords, headerLength, recordLength] = readFileInfo(fid); fieldInfo = getFieldInfo(fid); info.Filename = fopen(fid); info.DBFVersion = version; info.FileModDate = date; info.NumRecords = numRecords; info.NumFields = length(fieldInfo); info.FieldInfo = fieldInfo; info.HeaderLength = headerLength; info.RecordLength = recordLength; %---------------------------------------------------------------------------- function [version, date, numRecords, headerLength, recordLength] = readFileInfo(fid) % Read from File Header. fseek(fid,0,'bof'); version = fread(fid,1,'uint8'); year = fread(fid,1,'uint8') + 1900; month = fread(fid,1,'uint8'); day = fread(fid,1,'uint8'); dateVector = datevec(sprintf('%d/%d/%d',month,day,year)); dateForm = 1;% dd-mmm-yyyy date = datestr(dateVector,dateForm); numRecords = fread(fid,1,'uint32'); headerLength = fread(fid,1,'uint16'); recordLength = fread(fid,1,'uint16'); %---------------------------------------------------------------------------- function fieldInfo = getFieldInfo(fid) % Form FieldInfo by reading Field Descriptor Array. % % FieldInfo is a 1-by-numFields structure array with the following fields: % Name A string containing the field name % Type A string containing the field type % ConvFunc A function handle to convert from DBF to MATLAB type % Length A number equal to the length of the field in bytes lengthOfLeadingBlock = 32; lengthOfDescriptorBlock = 32; lengthOfTerminator = 1; fieldNameOffset = 16; % Within table field descriptor fieldNameLength = 11; % Get number of fields. fseek(fid,8,'bof'); headerLength = fread(fid,1,'uint16'); numFields = (headerLength - lengthOfLeadingBlock - lengthOfTerminator)... / lengthOfDescriptorBlock; % Read field lengths. fseek(fid,lengthOfLeadingBlock + fieldNameOffset,'bof'); lengths = fread(fid,[1 numFields],'uint8',lengthOfDescriptorBlock - 1); % Read the field names. fseek(fid,lengthOfLeadingBlock,'bof'); data = fread(fid,[fieldNameLength numFields],... sprintf('%d*uint8=>char',fieldNameLength),... lengthOfDescriptorBlock - fieldNameLength); data(data == 0) = ' '; % Replace nulls with blanks names = cellstr(data')'; % Read field types. fseek(fid,lengthOfLeadingBlock + fieldNameLength,'bof'); dbftypes = fread(