论坛 › Matlab讨论区 › 实验变差函数，输入变量赋值的问题!

漠漠之堡 发表于 2012-6-26 17:15

实验变差函数，输入变量赋值的问题!

各位高手，我现在有一个关于实验变差函数的代码，现在遇到一个问题：该如何给输入变量赋值？希望懂的人能帮我看看，多谢了！
function S = variogram(x,y,varargin)

% isotropic and anisotropic experimental (semi-)variogram
%
% Syntax:
% d = variogram(x,y)
% d = variogram(x,y,'propertyname','propertyvalue',...)
%
% Description:
% variogram calculates the experimental variogram in various
% dimensions.
%
% Input:
% x - array with coordinates. Each row is a location in a
% size(x,2)-dimensional space (e.g. )
% y - column vector with values of the locations in x.
%
% Propertyname/-value pairs:
% nrbins - number bins the distance should be grouped into
% (default = 20)
% maxdist - maximum distance for variogram calculation
% (default = maximum distance in the dataset / 2)
% type - 'gamma' returns the variogram value (default)
% 'cloud1' returns the binned variogram cloud
% 'cloud2' returns the variogram cloud
% plotit - true -> plot variogram
% false -> don't plot (default)
% subsample - number of randomly drawn points if large datasets are used.
% scalar (positive integer, e.g. 3000)
% inf (default) = no subsampling
% anisotropy - false (default), true (works only in two dimensions)
% thetastep - if anisotropy is set to true, specifying thetastep
% allows you the angle width (default 30?
%
%
% Output:
% d - structure array with distance and gamma - vector
%
% Example: Generate a random field with periodic variation in x direction
%
% x = rand(1000,1)*4-2;
% y = rand(1000,1)*4-2;
% z = 3*sin(x*15)+ randn(size(x));
%
% subplot(2,2,1)
% scatter(x,y,4,z,'filled'); box on;
% ylabel('y'); xlabel('x')
% title('data (coloring according to z-value)')
% subplot(2,2,2)
% hist(z,20)
% ylabel('frequency'); xlabel('z')
% title('histogram of z-values')
% subplot(2,2,3)
% d = variogram(,z,'plotit',true,'nrbins',50);
% title('Isotropic variogram')
% subplot(2,2,4)
% d2 = variogram(,z,'plotit',true,'nrbins',50,'anisotropy',true);
% title('Anisotropic variogram')
%
% Requirements:
% The function uses (objectId=10670)
% by Malcolm wood as subfunction.
%
% See also: KRIGING, VARIOGRAMFIT
%
% Date: 21. July, 2011
% Author: Wolfgang Schwanghart (w.schwanghartunibas.ch)


% error checking
if size(y,1) ~= size(x,1);
error('x and y must have the same number of rows')
end

% check for nans(非数值数)
II = any(isnan(x),2) | isnan(y);%这的关于x和y的表达为什么不同；
x(II,:) = [];
y(II) = [];

% extent of dataset（数据范围）
minx = min(x,[],1);
maxx = max(x,[],1);
maxd = sqrt(sum((maxx-minx).^2));%变差函数最大计算距离
nrdims = size(x,2);%2表示返回x的列数

% check input using PARSEARGS
params.nrbins = 20;
params.maxdist = maxd/2;
params.type = {'default','gamma','cloud1','cloud2'};
params.plotit = false;
params.anisotropy = false;
params.thetastep = 30;
params.subsample = inf;
params = parseargs(params,varargin{:});

if params.maxdist > maxd;
warning('Matlab:Variogram',...
['Maximum distance exceeds maximum distance \n' ...
'in the dataset. maxdist was decreased to ' num2str(maxd) ]);
params.maxdist = maxd;
end

if params.anisotropy && nrdims ~= 2
params.anisotropy = false;
warning('Matlab:Variogram',...
'Anistropy is only supported for 2D data');
end

% take only a subset of the data;
if ~isinf(params.subsample) && numel(y)>params.subsample;
IX = randperm(numel(y));%randperm:随机排列，随即置换
x = x(IX(1:params.subsample),:);
y = y(IX(1:params.subsample),:);
end

% calculate bin tolerance
tol = params.maxdist/params.nrbins;

% calculate distance matrix
iid = distmat(x,params.maxdist);

% calculate squared difference between values of coordinate pairs
lam = (y(iid(:,1))-y(iid(:,2))).^2;

% anisotropy
if params.anisotropy
nrthetaedges = floor(180/params.thetastep);

% calculate with radians, not degrees
params.thetastep = params.thetastep/180*pi;

% calculate angles, note that angle is calculated clockwise from top
theta = atan2(x(iid(:,2),1)-x(iid(:,1),1),...
x(iid(:,2),2)-x(iid(:,1),2));

% only the semicircle is necessary for the directions
I = theta < 0;
theta(I) = theta(I)+pi;
I = theta >= pi-params.thetastep/2;
theta(I) = 0;

% create a vector with edges for binning of theta
% directions go from 0 to 180 degrees;
thetaedges = linspace(-params.thetastep/2,pi-params.thetastep/2,nrthetaedges);

% bin theta
= histc(theta,thetaedges);

% bin centers
thetacents = thetaedges(1:end)+params.thetastep/2;
thetacents(end) = pi; %[];
end

% calculate variogram
switch params.type
case {'default','gamma'}
% variogram anonymous function
fvar = @(x) 1./(2*numel(x)) * sum(x);

% distance bins
edges = linspace(0,params.maxdist,params.nrbins+1);
edges(end) = inf;

= histc(iid(:,3),edges);

if params.anisotropy
S.val = accumarray(,lam,...
,fvar,nan);
S.val(:,end)=S.val(:,1);
S.theta = thetacents;
S.num = accumarray(,ones(size(lam)),...
,@sum,nan);
S.num(:,end)=S.num(:,1);
else
S.val = accumarray(ixedge,lam,,fvar,nan);
S.num = accumarray(ixedge,ones(size(lam)),,@sum,nan);
end
S.distance = (edges(1:end-1)+tol/2)';
S.val(end,:) = [];
S.num(end,:) = [];

case 'cloud1'
edges = linspace(0,params.maxdist,params.nrbins+1);
edges(end) = inf;

= histc(iid(:,3),edges);

S.distance = edges(ixedge) + tol/2;
S.distance = S.distance(:);
S.val = lam;
if params.anisotropy
S.theta = thetacents(ixtheta);
end
case 'cloud2'
S.distance = iid(:,3);
S.val = lam;
if params.anisotropy
S.theta = thetacents(ixtheta);
end
end


% create plot if desired
if params.plotit
switch params.type
case {'default','gamma'}
marker = 'o--';
otherwise
marker = '.';
end

if ~params.anisotropy
plot(S.distance,S.val,marker);
axis();
xlabel('h');
ylabel('\gamma (h)');
title('(Semi-)Variogram');
else
= pol2cart(repmat(S.theta,numel(S.distance),1),repmat(S.distance,1,numel(S.theta)));
surf(Xi,Yi,S.val)
xlabel('h y-direction')
ylabel('h x-direction')
zlabel('\gamma (h)')
title('directional variogram')
% set(gca,'DataAspectRatio',)
end
end

end


% subfunction distmat

function iid = distmat(X,dmax)

% constrained distance function
%
% iid ->


n = size(X,1);
nrdim = size(X,2);
if size(X,1) < 1000;
= find(triu(true(n)));
if nrdim == 1;
d = abs(X(i)-X(j));
elseif nrdim == 2;
d = hypot(X(i,1)-X(j,1),X(i,2)-X(j,2));
else
d = sqrt(sum((X(i,:)-X(j,:)).^2));
end
I = d<=dmax;
iid = ;
else
ix = (1:n)';
if nrdim == 1;
iid = arrayfun(@distmatsub1d,(1:n)','UniformOutput',false);
elseif nrdim == 2;
% if needed change distmatsub to distmatsub2d which is numerically
% better but slower
iid = arrayfun(@distmatsub,(1:n)','UniformOutput',false);
else
iid = arrayfun(@distmatsub,(1:n)','UniformOutput',false);
end
nn = cellfun(@(x) size(x,1),iid,'UniformOutput',true);
I = nn>0;
ix = ix(I);
nn = nn(I);
nncum = cumsum(nn);
c = zeros(nncum(end),1);
c() = 1;
i = ix(cumsum(c));
iid = ;

end

function iid = distmatsub1d(i)
j = (i+1:n)';
d = abs(X(i)-X(j));
I = d<=dmax;
iid = ;
end

function iid = distmatsub2d(i) %#ok<DEFNU>
j = (i+1:n)';
d = hypot(X(i,1) - X(j,1),X(i,2) - X(j,2));
I = d<=dmax;
iid = ;
end

function iid = distmatsub(i)
j = (i+1:n)';
d = sqrt(sum(bsxfun(@minus,X(i,:),X(j,:)).^2,2));
I = d<=dmax;
iid = ;
end
end



% subfunction parseargs

function X = parseargs(X,varargin)

%PARSEARGS - Parses name-value pairs
%
% Behaves like setfield, but accepts multiple name-value pairs and provides
% some additional features:
% 1) If any field of X is an cell-array of strings, it can only be set to
% one of those strings. If no value is specified for that field, the
% first string is selected.
% 2) Where the field is not empty, its data type cannot be changed
% 3) Where the field contains a scalar, its size cannot be changed.
%
% X = parseargs(X,name1,value1,name2,value2,...)
%
% Intended for use as an argument parser for functions which multiple options.
% Example usage:
%
% function my_function(varargin)
% X.StartValue = 0;
% X.StopOnError = false;
% X.SolverType = {'fixedstep','variablestep'};
% X.OutputFile = 'out.txt';
% X = parseargs(X,varargin{:});
%
% Then call (e.g.):
%
% my_function('OutputFile','out2.txt','SolverType','variablestep');

% The various #ok comments below are to stop MLint complaining about
% inefficient usage. In all cases, the inefficient usage (of error, getfield,
% setfield and find) is used to ensure compatibility with earlier versions
% of MATLAB.

remaining = nargin-1; % number of arguments other than X
count = 1;
fields = fieldnames(X);
modified = zeros(size(fields));
% Take input arguments two at a time until we run out.
while remaining>=2
fieldname = varargin{count};
fieldind = find(strcmp(fieldname,fields));
if ~isempty(fieldind)
oldvalue = getfield(X,fieldname); %#ok
newvalue = varargin{count+1};
if iscell(oldvalue)
% Cell arrays must contain strings, and the new value must be
% a string which appears in the list.
if ~iscellstr(oldvalue)
error(sprintf('All allowed values for "%s" must be strings',fieldname)); %#ok
end
if ~ischar(newvalue)
error(sprintf('New value for "%s" must be a string',fieldname)); %#ok
end
if isempty(find(strcmp(oldvalue,newvalue))) %#ok
error(sprintf('"%s" is not allowed for field "%s"',newvalue,fieldname)); %#ok
end
elseif ~isempty(oldvalue)
% The caller isn't allowed to change the data type of a non-empty property,
% and scalars must remain as scalars.
if ~strcmp(class(oldvalue),class(newvalue))
error(sprintf('Cannot change class of field "%s" from "%s" to "%s"',...
fieldname,class(oldvalue),class(newvalue))); %#ok
elseif numel(oldvalue)==1 & numel(newvalue)~=1 %#ok
error(sprintf('New value for "%s" must be a scalar',fieldname)); %#ok
end
end
X = setfield(X,fieldname,newvalue); %#ok
modified(fieldind) = 1;
else
error(['Not a valid field name: ' fieldname]);
end
remaining = remaining - 2;
count = count + 2;
end
% Check that we had a value for every name.
if remaining~=0
error('Odd number of arguments supplied. Name-value pairs required');
end

% Now find cell arrays which were not modified by the above process, and select
% the first string.
notmodified = find(~modified);
for i=1:length(notmodified)
fieldname = fields{notmodified(i)};
oldvalue = getfield(X,fieldname); %#ok
if iscell(oldvalue)
if ~iscellstr(oldvalue)
error(sprintf('All allowed values for "%s" must be strings',fieldname)); %#ok
elseif isempty(oldvalue)
error(sprintf('Empty cell array not allowed for field "%s"',fieldname)); %#ok
end
X = setfield(X,fieldname,oldvalue{1}); %#ok
end
end
end

漠漠之堡 发表于 2012-6-27 08:38

自己先顶一下，希望大家尽快看到，帮忙解决一下，多谢了！！！！

ChaChing 发表于 2012-6-27 11:23

该如何给输入变量赋值？
个人水平有限, 真不懂LZ的意思!?
LZ的函数裡头不是有说明及例子了?:@)

漠漠之堡 发表于 2012-6-27 14:53

回复 3 # ChaChing 的帖子

实例是一个script文件，这个程序本身是函数文件，输入变量x,y不是随机生成的量，是要从外部输入的，是大批量数据，在command窗口直接输入不现实，所以我就想问如何给输入变量赋值。

ChaChing 发表于 2012-6-27 16:06

本帖最后由 ChaChing 于 2012-6-27 16:07 编辑

回复 4 # 漠漠之堡 的帖子

Ref: 3.[原创]使用文本文件(.txt)进行数据存取的技巧总结 http://forum.vibunion.com/thread-45622-1-1.html
   也谈在Matlab中读入数字与字符混排的文本数据 http://forum.vibunion.com/thread-8937-1-1.html
   [转帖]matlab中常见txt文件读入的实用方法 http://forum.vibunion.com/thread-2029-1-1.html
   在Matlab中读入数字与字符混排的文本数据 http://forum.vibunion.com/thread-7985-1-1.html
   如何导入大量数据 http://forum.vibunion.com/thread-104333-1-2.html
From http://forum.vibunion.com/home-space-uid-63979-do-blog-id-18250.html

漠漠之堡 发表于 2012-6-27 23:21

回复 5 # ChaChing 的帖子

:time:学习下，多谢了！

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