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How to import column data from multiple Excel files with different number of rows?

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Jose Rubio
Jose Rubio 2019-3-14
评论： Jose Rubio 2019-3-14
I have n Excels files which I need to copy and store their data into Matlab. In each Excel file, the first column represents a specific variable, e.g., "Time", and the second column is another variable, e.g., "Displacement". Each of these Excel files has the same number of columns but different number of rows. For instance, file-1 has 100 rows, but file-2 has 150 rows. Using the code below (named PlotAll), I get the following error:
Subscripted assignment dimension mismatch.
Error in PlotAll
Time (:,K) =data(:,1);
How can I solve this error? I believe it's related to having an array which changes size in the "for" loop, but I don't know how to solve it.
Thanks,
clc
clear all
close all
fnames = dir('*.xls');
numfids = length(fnames);
for K = 1:numfids
data = xlsread(fnames(K).name);
Time(:,K)=data(:,1);
Displacement(:,K)=data(:,2);
end
  2 个评论
Jan
Jan 2019-3-14
The brute clearing header "clc, clear all, close all" does not offer any benefits here. Therefore it is a cargo cult programming (link): It migt have been useful anywhere else, so repeat it, even if it does not have any meaning here. Beside this, it wastes a lot of time by removing all loaded functions from the memory. Reloading them from the slow disk is time-consuming.

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采纳的回答

Fangjun Jiang
Fangjun Jiang 2019-3-14
Since each file contains different number of rows, you will need to use cell array for this. Change inside the loop to
Time{K}=data(:,1);
Displacement{K}=data(:,2);
It is better to pre-allocate before the loop
Time=cell(size(fnames));
Displacement=cell(size(fnames));
When using the data
plot(Time{K},Displacement{K})

更多回答（1 个）

Easwar Kumar Yarrabikki
%%You can try something like this, Just finding the length of vector and defining the sizes
clc
clear all
close all
fnames = dir('*.xlsx');
numfids = length(fnames);
Time=[];
Displacement=[];
for K = 1:numfids
data = xlsread(fnames(K).name);
row_length=length(data(:,1));
Time(1:row_length,K)=data(:,1);
row_length1=length(data(:,2));
Displacement(1:row_length1,K)=data(:,2);
end
  2 个评论
Jan
Jan 2019-3-14
Use size(data, 1) instead of length(data(:,1)), because the latter wastes time with creating a temporary vector only to count its elements. size can solve this directly.
Jose Rubio
Jose Rubio 2019-3-14
Thanks for the quick response Easwar and Jan. This code works.
I followed Jan's suggestion and replace length(data(:,1)) with (data, 1) and it works as well.

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