Matlab interp1 将最后一行作为 NaN

Question

我遇到了类似于 here 的问题。不过好像没有解决办法。

我的问题是这样的：我需要导入一些文件，比如5个，每个文件有20列，但是行数不一样。第一列是曲柄转角时间，其余为数据。

所以我的代码首先导入所有文件，找到行数最多的文件，然后创建一个包含那么多行的多维数组。时间是在引擎循环中，所以我会从导入的文件中删除超出整个引擎循环的行。这样，我总是有 X 个整个引擎循环的数据。然后我将数据插入到预先分配的数组中，为 5 个数据文件提供一个巨大的多维数组。

然而，这似乎总是导致每页每列的最后一行都被 NaN 填充。请看下面的代码。我看不出我哪里做错了。哦，顺便说一句，因为我之前被搞砸了，这不是作业。

maxlines = 0;
maxcycle = 999;
for i = 1:1
    filename = sprintf('C:\Directory\%s\file.out',folder{i});
    file = filelines(filename); % Import file clean
    lines = size(file,1); % Find number of lines of file
    if lines > maxlines
        maxlines = lines; % If number of lines in this file is the most, save it
    end
    lastCAD = file(end,1); % Add simstart to shift the start of the cycle to 0 CAD
    lastcycle = fix((lastCAD-simstart)./cycle); % Find number of whole engine cycles
    if lastcycle < maxcycle
        maxcycle = lastcycle; % Find lowest number of whole engine cycles amongst all designs
    end
    cols = size(file,2); % Find number of columns in files
end

lastcycleCAD = maxcycle.*cycle+simstart; % Define last CAD of whole cycle that can be used for analysis

% Import files
thermo = zeros(maxlines,cols,designs); % Initialize array to proper size
xq = linspace(simstart,lastcycleCAD,maxlines); % Define the CAD degrees
for i = 1:designs
    filename = sprintf('C:\Directory\%s\file.out',folder{i});
    file = importthermo(filename, 6, inf); % Import the file clean
    [~,lastcycleindex] = min(abs(file(:,1)-lastcycleCAD)); % Find index of end of last whole cycle
    file = file(1:lastcycleindex,:); % Remove all CAD after that
    thermo(:,1,i) = xq;
    for j = 2:17
        thermo(:,j,i) = interp1(file(:,1),file(:,j),xq);
    end
    sprintf('file from folder %s imported OK',folder{i})
end

thermo(end,:,:) = []; % Remove NaN row

非常感谢您的帮助！

Answer 1

您的采样是否超出范围？如果是这样，您需要告诉 interp1 您想要外推

 interp1(file(:,1),file(:,j),xq,'linear','extrap');

Matlab interp1 将最后一行作为 NaN

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