www.gusucode.com > datastoreio工具箱 matlab源码程序 > datastoreio/+matlab/+io/+datastore/@FileDatastore/FileDatastore.m
classdef (Sealed) FileDatastore < ...
matlab.io.datastore.CustomReadDatastore & ...
matlab.io.datastore.internal.ScalarBase & ...
matlab.mixin.CustomDisplay
%FILEDATASTORE Datastore for a collection of files with custom data format.
% FDS = fileDatastore(LOCATION,'ReadFcn',@MYCUSTOMREADER) creates a
% FileDatastore if a file or a collection of files are present in LOCATION.
% LOCATION has the following properties:
% - Can be a filename or a folder name
% - Can be a cell array of multiple file or folder names
% - Can contain a relative path (HDFS requires a full path)
% - Can contain a wildcard (*) character.
% 'ReadFcn',@MYCUSTOMREADER Name-Value pair specifies the user-defined
% function to read files. The value of 'ReadFcn' must be a function handle
% with a signature similar to the following:
% function data = MYCUSTOMREADER(filename)
% ..
% end
%
% FDS = fileDatastore(__,'IncludeSubfolders',TF) specifies the logical
% true or false to indicate whether the files in each folder and its
% subfolders are included recursively or not.
%
% FDS = fileDatastore(__,'FileExtensions',EXTENSIONS) specifies the
% extensions of files to be included. Values for EXTENSIONS can be:
% - A character vector, such as '.jpg' or '.png' (empty quotes '' are
% allowed for files without extensions)
% - A cell array of character vectors, such as {'.jpg', '.mat'}
%
% FileDatastore Properties:
%
% Files - Cell array of file names
% ReadFcn - Function handle used to read files
%
% FileDatastore Methods:
%
% hasdata - Returns true if there is more data in the datastore
% read - Reads the next consecutive file
% reset - Resets the datastore to the start of the data
% preview - Reads the first file from the datastore for preview
% readall - Reads all of the files from the datastore
% partition - Returns a new datastore that represents a single
% partitioned portion of the original datastore
% numpartitions - Returns an estimate for a reasonable number of
% partitions according to the total data size to use
% with the partition function
%
% Example:
% --------
% folder = fullfile(matlabroot,'toolbox','matlab','demos');
% fds = fileDatastore(folder,'ReadFcn',@load,'FileExtensions','.mat');
%
% data1 = read(fds); % Read the first MAT-file
% data2 = read(fds); % Read the next MAT-file
% readall(fds) % Read all of the MAT-files
% dataArr = cell(numel(fds.Files),1);
% i = 1;
% reset(fds); % Reset to the beginning of data
% while hasdata(fds) % Read files using a while-loop
% dataArr{i} = read(fds);
% i = i + 1;
% end
%
% See also datastore, mapreduce, load, fileDatastore.
% Copyright 2015 The MathWorks, Inc.
properties (Dependent)
%Files -
% A cell array of file names.
Files;
end
properties (Access = private)
% deployement needs a way to get files before resolving them
UnResolvedFiles;
end
properties (Constant, Access = private)
WHOLE_FILE_CUSTOM_READ_SPLITTER_NAME = 'matlab.io.datastore.splitter.WholeFileCustomReadSplitter';
CONVENIENCE_CONSTRUCTOR_FCN_NAME = 'fileDatastore';
end
% Constructor
methods
% FileDataStore can be constructed with files argument, optionally
% with ReadFcn, IncludeSubfolders, FileExtensions Name-Value pairs.
function fds = FileDatastore(files, varargin)
try
import matlab.io.datastore.FileDatastore;
nv = iParseNameValues(varargin{:});
initDatastore(fds, files, nv);
fds.UnResolvedFiles = files;
catch e
throwAsCaller(e);
end
end
end
% Set and Get methods for properties
methods
% Set method for Files
function set.Files(fds, files)
try
setNewFilesAndFileSizes(fds, files);
catch e
throw(e)
end
end
% Get Files
function files = get.Files(fds)
files = fds.Splitter.Files;
end
end
methods (Access = private)
function initDatastore(fds, files, nv)
import matlab.io.datastore.FileDatastore;
import matlab.io.datastore.internal.validators.validateCustomReadFcn;
readFcn = nv.ReadFcn;
if ismember('ReadFcn', nv.UsingDefaults) && ...
isnumeric(readFcn) && readFcn == -1
error(message('MATLAB:datastoreio:filedatastore:readFcnNotProvided'));
end
validateCustomReadFcn(readFcn, true, FileDatastore.CONVENIENCE_CONSTRUCTOR_FCN_NAME);
[~, files, fileSizes] = FileDatastore.supportsLocationHelper(files, nv);
fds.SplitterName = FileDatastore.WHOLE_FILE_CUSTOM_READ_SPLITTER_NAME;
% Files are resolved @supportsLocationHelper
resolved = true;
initFromReadFcn(fds, readFcn, files, fileSizes, nv.IncludeSubfolders);
end
end
methods (Access = protected)
function validateReadFcn(~, readFcn)
import matlab.io.datastore.FileDatastore;
import matlab.io.datastore.internal.validators.validateCustomReadFcn;
validateCustomReadFcn(readFcn, false, FileDatastore.CONVENIENCE_CONSTRUCTOR_FCN_NAME);
end
function displayScalarObject(fds)
% header
disp(getHeader(fds));
group = getPropertyGroups(fds);
detailsStr = evalc('details(fds)');
nsplits = strsplit(detailsStr, '\n');
filesStr = nsplits(~cellfun(@isempty, strfind(nsplits, 'Files: ')));
% Find the indent spaces from details
nFilesIndent = strfind(filesStr{1}, 'Files: ') - 1;
if nFilesIndent > 0
% File Properties
filesIndent = [sprintf(repmat(' ',1,nFilesIndent)) 'Files: '];
nlspacing = sprintf(repmat(' ',1,numel(filesIndent)));
if isempty(fds.Files)
nlspacing = '';
end
import matlab.io.datastore.internal.cellArrayDisp;
filesStrDisp = cellArrayDisp(fds.Files, true, nlspacing);
disp([filesIndent filesStrDisp]);
% Remove Files property from the group, since custom
% display is used for Files.
group.PropertyList = rmfield(group.PropertyList, 'Files');
end
matlab.mixin.CustomDisplay.displayPropertyGroups(fds, group);
disp(getFooter(fds));
end
end
methods (Hidden)
function files = getUnresolvedFiles(fds)
files = fds.UnResolvedFiles;
end
end
methods (Static, Hidden)
function tf = supportsLocation(~, ~)
% This function is responsible for determining whether a given
% location is supported by FileDatastore. For FileDatastore
% 'Type' Name-Value pair must be provided for datastore function.
tf = false;
end
function varargout = supportsLocationHelper(loc, nvStruct)
% This function is responsible for determining whether a given
% location is supported by FileDatastore. It also returns a
% resolved filelist.
defaultExtensions = {};
% validate file extensions, include subfolders is validated in
% pathlookup
import matlab.io.datastore.internal.validators.validateFileExtensions;
import matlab.io.datastore.FileBasedDatastore;
isDefaultExts = validateFileExtensions(nvStruct.FileExtensions, nvStruct.UsingDefaults);
[varargout{1:nargout}] = FileBasedDatastore.supportsLocation(loc, nvStruct, defaultExtensions, ~isDefaultExts);
end
function outds = loadobj(ds)
if ds.Splitter.NumSplits ~= 0
% create a split reader that points to the
% first split index.
if ds.SplitIdx == 0
ds.SplitIdx = 1;
end
ds.SplitReader = ds.Splitter.createReader(ds.SplitIdx);
end
outds = loadobj@matlab.io.datastore.FileBasedDatastore(ds);
end
end
end
function parsedStruct = iParseNameValues(varargin)
persistent inpP;
if isempty(inpP)
import matlab.io.datastore.FileDatastore;
inpP = inputParser;
addParameter(inpP, 'ReadFcn', -1);
addParameter(inpP, 'IncludeSubfolders', false);
addParameter(inpP, 'FileExtensions', -1);
inpP.FunctionName = FileDatastore.CONVENIENCE_CONSTRUCTOR_FCN_NAME;
end
parse(inpP, varargin{:});
parsedStruct = inpP.Results;
parsedStruct.UsingDefaults = inpP.UsingDefaults;
end