How to populate array with column vectors of different lengths

Question

Erik Hopkins 2020-4-20

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/519392-how-to-populate-array-with-column-vectors-of-different-lengths

编辑： the cyclist 2020-4-20

I have an 8635x9 array of AFM data, ind_F, where each column is an indentation force curve. I'm having two major problems with the data set:

1) plot(Ind_F) will plot the 9 indentations but each trace begins increasing at different X values (see first attached graph).

I would like to align all the traces such that they start increasing at the same X value. I think I solved this with a for loop that recognizes the X index where the trace crosses a set threshold, cut, and plots from there, but I feel there's a more efficent way to do this.

cut = 2*10^-10; %set threshold to determine where curve starts
spacer = 500; %spacer from Y axis
for i = 1:size(ind_F,2)
    ind_F_logical = ind_F > cut;
    [i_upstart i_trace] = find(ind_F_logical(:,i),1,'first'); %find X index where trace crosses threshold
 
   hold on
   plot(ind_F(i_upstart-spacer:end, i));
   hold off
end

2) I also want an array with these aligned trace values but each vector will be a different length. I was thinking of elongating shorter vectors with NaNs but cant figure out howt to do that.

Thanks!

2 个评论
显示无隐藏无

the cyclist 2020-4-20

Can you upload your data in a MAT file (using the paper-clip icon)?

Erik Hopkins 2020-4-20

ind_F.mat

here's the data file

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

the cyclist 2020-4-20

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/519392-how-to-populate-array-with-column-vectors-of-different-lengths#answer_427190

I think this does what you want, in a slightly less complicated way:

figure
hold on
for i = 1:size(ind_F,2)
    plot(ind_F(ind_F(:,i)>=cut,i))
end

(I didn't add in the "spacer".)

2 个评论
显示无隐藏无

Erik Hopkins 2020-4-20

yes, thanks. This does it in a much simpler way. I'm still stuck on creating a new array with these aligned traces however

the cyclist 2020-4-20

编辑：the cyclist 2020-4-20

new_ind_F = nan(size(ind_F));
figure
hold on
for i = 1:size(ind_F,2)
    this_vec = ind_F(ind_F(:,i)>=cut,i);
    new_ind_F(1:size(this_vec),i) = this_vec;
end
plot(new_ind_F)