CSV file import in Matlab
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Corentin Hurel
on 29 Jun 2017
Commented: Corentin Hurel
on 30 Jun 2017
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 :
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/165642/image.png)
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 !
5 Comments
Accepted Answer
Guillaume
on 30 Jun 2017
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.
More Answers (1)
Ari
on 29 Jun 2017
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
4 Comments
Guillaume
on 30 Jun 2017
Well, what should happen with these multiple rows in these subcells? Convert them into rows into the main cell array?
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