CSV file import in Matlab

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Corentin Hurel
Corentin Hurel 2017-6-29
评论： Corentin Hurel 2017-6-30
Hello everybody,
I have to import data from multiple csv files (more than 4000). Each csv file contains 7 columns, between 1 and 6 rows and 1 header-line. It contains multiple types of data, this format : formatSpec = '%f %f %f %s %f %f %f'. I used this to extract the data :
%%How many file ?
files = dir('C:\Users\titin\Documents\MATLAB\UALG\RADAR07\*csv');
num_files = length(files);
%%Extract data from files
for i=1:num_files
for j=1:1
% open files
fid = fopen(files(i).name
% read data from csv file
readData = textscan(fid,'%f %f %f %s %f %f %f','HeaderLines',1,'Delimiter',',','TextType','string','ReturnOnError',false,'EndOfLine','\r\n');
% extract data from readData
UserID(i,j) = readData(1,1);
Longitude(i,j) = readData(1,2);
Latitude(i,j) = readData(1,3);
Timestamp(i,j) = readData(1,4);
SpeedOverGround(i,j) = readData(1,5);
NavigationStatus(i,j) = readData(1,6);
ShipType(i,j) = readData(1,7);
end
end
The problem is, when I have a csv file which have more than 1 rows it creates a cell into an another cell like this :
For the numeric cell its not a problem because I used the function : cell2mat, and each cell was divided. But for the string cell, I don't know how to proceed to not have cells into cells. I tried to use the function cellstr but when there is a cell into cell I have an error.
If someone can help it would be great !
Thanks !
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Guillaume
Guillaume 2017-6-30
We need an example file that shows the problem.
Any reason you're not using readtable to do the parsing for you?

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采纳的回答

Guillaume
Guillaume 2017-6-30
Assuming you just want the multiple rows in the sub-cells to be converted into rows in the main array, and assuming that the main cell array is indeed a column cell vector (i.e. Nx1) and the subcells are also column cell vectors, then
if any(cellfun(@iscell, yourcellarray))
yourcellarray = vertcat(yourcellarray{:});
end
But you'd be better off fixing the import, something we can only help with if we have an example of a file causing problem.
Even better would be to use readtable to do the parsing for you.
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Corentin Hurel
Corentin Hurel 2017-6-30
Thanks for this answer, this was exactly what I needed!
Regards

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更多回答（1 个）

Ari
Ari 2017-6-29
The function textscan returns data into a string or cell array, and when you have multiple rows in your csv files it will return a cell array. To access the contents of a cell array you can use the { } operator. For example you can use the following in your code:
TimestampArray = readData(1,4);
TimestampStrings = TimestampArray{:};
Now TimestampStrings will be a Nx1 string array, you can access the elements using
ithTimestamp = TimestampStrings(i); % where i is an integer
For more details on indexing matrix and cell array, view the documentation here.
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Corentin Hurel
Corentin Hurel 2017-6-30
Hello, Thanks for your answer !
I have a cell array named TimestampArray that contains 109 rows of string. In certains cell i have an another cell with multiple rows. I want to have just an array of string without cells into cells.
Do you know how to do this?
Regards
Guillaume
Guillaume 2017-6-30
Well, what should happen with these multiple rows in these subcells? Convert them into rows into the main cell array?

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