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CSVIMPORT

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CSVIMPORT

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06 Apr 2009 (Updated )

CSVIMPORT reads the specified CSV file and stores the contents in a cell array or matrix.

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Description

  CSVIMPORT reads the specified CSV file and stores the contents in a cell array or matrix
 
  The file can contain any combination of text & numeric values. Output data format will vary
  depending on the exact composition of the file data.
 
  CSVIMPORT( fileName ): fileName - String specifying the CSV file to be read. Set to
                    [] to interactively select the file.
 
  CSVIMPORT( fileName, ... ) : Specify a list of options to be applied when importing the CSV file.
                    The possible options are:
                    delimiter - String to be used as column delimiter. Default
                    value is , (comma)
                    columns - String or cell array of strings listing the columns
                    from which data is to be extracted. If omitted data
                    from all columns in the file is imported. If file
                    does not contain a header row, the columns
                    parameter can be a numeric array listing column
                    indices from which data is to be extracted.
                    outputAsChar - true / false value indicating whether the data
                    should be output as characters. If set to false the
                    function attempts to convert each column into a
                    numeric array, it outputs the column as characters
                    if conversion of any data element in the column
                    fails. Default value is false.
                    uniformOutput - true / false value indicating whether output can be
                    returned without encapsulation in a cell array.
                    This parameter is ignored if the columns / table
                    cannot be converted into a matrix.
                    noHeader - true / false value indicating whether the CSV
                    file's first line contains column headings. Default
                    value is false.
                    ignoreWSpace - true / false value indicating whether to ignore
                    leading and trailing whitespace in the column
                    headers; ignored if noHeader is set to true.
                    Default value is false.
 
  The parameters must be specified in the form of param-value pairs, parameter names are not
  case-sensitive and partial matching is supported.
 
  [C1 C2 C3] = CSVIMPORT( fileName, 'columns', {'C1', 'C2', C3'}, ... )
    This form returns the data from columns in output variables C1, C2 and C3 respectively, the
    column names are case-sensitive and must match a column name in the file exactly. When fetching
    data in column mode the number of output columns must match the number of columns to read or it
    must be one. In the latter case the data from the columns is returned as a single cell matrix.
 
  [C1 C2 C3] = CSVIMPORT( fileName, 'columns', [1, 3, 4], ,'noHeader', true, ... )
    This form returns the data from columns in output variables C1, C2 and C3 respectively, the
    columns parameter must contain the column indices when the 'noHeader' option is set to true.

Notes: 1. Function has not been tested on badly formatted CSV files.
            2. Created using R2007b but has been tested on R2006b.

MATLAB release MATLAB 7.5 (R2007b)
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Comments and Ratings (45)
22 May 2015 Ashish Sadanandan

@SK

Sorry, but that's unlikely to happen. I no longer have access to MATLAB, and in any case, going down the rabbit hole of handling delimiters escaped in various ways is not something I'm keen on doing.

Comment only
21 May 2015 SK

SK (view profile)

There is an issue you may want to fix. Commas inside a quoted value should be ignored.

19 May 2015 Sagarika Kadambi

@Anish Sadanandan I ended up using something else because it just took way too long in the end for huge CSV's, but thanks anyway! It worked very well for smaller CSV's, thank you!!

15 May 2015 Ashish Sadanandan

@Sagarika Kadambi

There is no size limitation built into the function, but I've never tested it with files that large. You could try setting the 'outputAsChar' option to true, which should reduce memory requirements. Or try playing with a few different file sizes, for e.g. reduce to 450,000 lines, if it works, try 700,000, if it doesn't 300,000 and so.

Sorry I don't have a definite answer for you.

Comment only
15 May 2015 Sagarika Kadambi

Hi,
Does this work for very large csv files? I'm trying to use one that is about 900,000 lines, and the function simply doesn't work..

I'm using
[C2 C3] = csvimport('testCSV.csv','columns',2:3,'noHeader',true)

and it works for me and prints out something like:

C1 =
234234
364565
4744562
234123
235346
142314

C2 =
453466
234636
86789
878
234265
124346

which is what I want... but if I do it with the bigger csv file, it just prints out a list of numbers like:

234234
23425
53456
456457
456547

and so on..

my data looks something like this:

2014-6-06 08:03:19, 439105, 1053224, Front Entrance

2014-6-06 09:43:21, 439105, 1696241, Main Exit

2014-6-06 10:01:54, 1836139, 1593258, Back Archway

2014-6-06 04:45:13, 1464748, 439105, Side Exit

Am I doing something wrong?

Comment only
18 Mar 2015 Stefan Toussaint

This is great. Thank you

04 Mar 2015 Justin

Justin (view profile)

Simply Awesome. much improved over the woeful csvread function...

25 Jan 2015 docsam

docsam (view profile)

Great work Ashish.. very useful, saved me a lot of h.assle

24 Jan 2015 Michelle

Very nice! In case it's helpful to anybody else, I was able to import data with missing values directly without the need to convert afterwards by changing line 284 from

if ~any( cellfun( @isnan, colData ) )

to

if ~any( cellfun( @isnan, colData ) & ~strcmp(data(startRowIdx:end,ii),'#N/A') & ~strcmp(data(startRowIdx:end,ii),'#n/a') )

09 Jan 2015 Jochen Willig  
28 Sep 2014 stijn

stijn (view profile)

 
16 Sep 2014 Oscar

Oscar (view profile)

 
31 Jul 2014 azizullah khan

sir, if csvexport is kindly share it with me..i am facing a problem with csvwirte i.e Error using dlmwrite (line 112)
The input cell array cannot be converted to a matrix.

31 Jul 2014 Adam Li

Adam Li (view profile)

Great code!

Only issue I really don't understand is why I have to save the file as a Windows CSV file in order for it to work. My code didn't work when the files were saved as only CSV; the column vectors came back empty. Do you think you would be able to fix this problem?

Thanks!

16 Jul 2014 Ashish Sadanandan

@Fan
Try adding a newline to the end of the file

Comment only
16 Jul 2014 Fan

Fan (view profile)

Works, any idea why it does not import the last row of the data?

10 Jul 2014 Poolla

Poolla (view profile)

Awesome, saves lot of otherwise work. Keep it up!

09 Jul 2014 Ged Ridgway

Ged Ridgway (view profile)

@Marcos, I had a similar problem, which seems to be fixed by adding a carriage return at the end of the csv file (e.g. using the MATLAB editor).

Comment only
13 Jun 2014 Marcos

Marcos (view profile)

Fantastic function, but I am confused by it's behavior with one of the files I need to import.

The format is
# header1 header2 ..... headern
1 v1..............v2.................vn
2 v1..............v2.................vn
.
.
.
11 v1..............v2.................vn

The values are mixed between numeric and chars, but the function only imports the first 11 rows, including the header, so the entire bottom row that starts with 11 is missing.

If I set 'noHeader' to true, then I get all 11 rows with values. I would prefer to not have to do this, so can someone explain why this would be happening?

18 Mar 2014 jason

jason (view profile)

Pretty cool function. However, It would be nice if it called the imported date by the orginal file name and not 'ans'

24 Oct 2013 DBS

DBS (view profile)

 
03 Oct 2013 Greg

Greg (view profile)

Added support for commas that are in between double quotes. so that they stay in one cell. First it replaces commas than are not in between quotes to semicolons, then splits by semicolons. Then removes the quotes. Starts at line 246 (the main for loop)

rowData = fgetl( fid );
if isempty( rowData )
emptyRowsIdx = [emptyRowsIdx(:); ii];
continue
end
%*** added by GSS
repIdx = regexp(rowData, '(?:^|,)(?:"((?:[^"]|"")*)"|([^",]*))');
rowData(repIdx(2:end))=';';
rowData = regexp(rowData,';','split');
for j=1:length(rowData)
if ~isempty(rowData{j}) && rowData{j}(1)=='"'
rowData{j}(1)=[];
rowData{j}(end)=[];
end
end
%****end GSS
nDataElems = numel( rowData );

Comment only
04 Jul 2013 Jason Kreykes

Some of the entries in the first column of my data contain a comma that should not be interpreted as a delimiter.

For example, the first three rows (with header row) are:
"School","Section Discipline"
"ACS Cogham International HS, UK","Physics"
"Adelphi University","Mathematics"

Can this be accomodated easily?

Comment only
12 Jun 2013 Dimid Duchovny

Works great. Thanks you!

09 May 2013 vlema

vlema (view profile)

Great function! It worked in a badly formatted csv file. thanks for sharing.

Comment only
01 Apr 2013 Chris

Chris (view profile)

@Bernoulli Lizard: As Warwick said, if you're a Mac user you need to change the csv to a Windows format. If you you have Perl, using this line in a terminal will do:
perl -p -i -e 's/\r/\n/g' *.csv

Comment only
05 Jan 2013 Steven Mvuyana

Good day Ashish

Why does the file convert the first colunm to char type?

Excellent CSV import function. Thank you.

Comment only
02 Oct 2012 Bernoulli Lizard

Chris, what did you do to read more than the first row? I'm having the same problem.

Comment only
25 May 2012 Ashish Sadanandan

Hi Sayanta,
Call the function as follows:

[C1 C2 C3 C4 C5] = csvimport( 'path\to\file.csv', 'columns', [1:5], 'noHeader', true, 'delimiter', ';' )

Comment only
22 May 2012 Sayanta

Hello Asish,

Here is the data I want to parse / import with mat lab code. I try to
use your function

[C1] = CSVIMPORT( 'CPU.csv', 'columns',{} );

Here is my data

Patrol7;/NT_CPU/CPU_0/CPUprcrInterruptsPerSec;04/04/2012;11:04:46;77

Patrol7;/NT_CPU/CPU_0/CPUprcrInterruptsPerSec;
04/04/2012;11:04:47;66.9016

Patrol7;/NT_CPU/CPU_0/CPUprcrInterruptsPerSec;
04/04/2012;11:04:47;67.0833

Patrol7;/NT_CPU/CPU_0/CPUprcrInterruptsPerSec;04/04/2012;11:04:47;66.1

Patrol7;/NT_CPU/CPU_0/CPUprcrInterruptsPerSec;
04/04/2012;11:04:48;66.3115

Patrol7;/NT_CPU/CPU_0/CPUprcrInterruptsPerSec;
04/04/2012;11:04:49;66.3934

Patrol7;/NT_CPU/CPU_0/CPUprcrInterruptsPerSec;
04/04/2012;11:04:49;86.8525

Patrol7;/NT_CPU/CPU_0/CPUprcrInterruptsPerSec;
04/04/2012;11:04:49;78.7288

Patrol7;/NT_CPU/CPU_0/CPUprcrInterruptsPerSec;
04/04/2012;11:04:50;66.4918

I'm getting all data in C1 cell. I want my data (Delimited) in C1 C2 C3 C4 C5 in 5 different cell.

Could you please tell me how can I resolve my problem

Thanks in advance
Sayanta

Comment only
19 Feb 2012 Ben

Ben (view profile)

You rock! Thank you. The best csv-import function out there.

29 Aug 2011 Warwick

If your'e a Mac user - I found that I had to save the .csv file as a "Windows comma delimted csv" file beforehand. Then it works superbly.

12 Aug 2011 Yuri K

Yuri K (view profile)

I get a figure window open during this function run at line 275. It appears that I had a string 'White(some information)' that probably runs function white. Anyway to prevent such behavior?

Comment only
15 Jul 2011 Cheol Hee

Very nice!!! But data replaced some numbers. Fantastic!!

15 Jul 2011 Cheol Hee  
10 Jun 2011 Chris

Chris (view profile)

I got it figured out. Works great!

10 Jun 2011 Chris

Chris (view profile)

It's only reading in the first row. Am I mixing up an argument? My .csv uses commas as the delimiter (obviously) but also has a 'return' to separate each row. Is this valid? Thanks.

Comment only
05 May 2011 Mais

Mais (view profile)

well done! best csv-import function, i found here!

08 Apr 2011 Christopher Hummersone

Fantastic!

14 Dec 2009 Gordon

Gordon (view profile)

This only worked on ascii files, but combined with unicode2ascii
it did a fantastic job.

18 Nov 2009 Gordon

Gordon (view profile)

Hi

Is it possible to use this code, or anything else for a csv file available on the web, ie:

http://www.google.com/insights/search/overviewReport?q=matlab&geo=US&cmpt=q&content=1&export=2

thanks

Comment only
28 Oct 2009 Ashish Sadanandan

Maney,
Try running 'which -all isscalar' at the command line, if MATLAB doesn't find any function by that name then you're either using an old version which doesn't have this function or you have problems with the MATLAB search path. Let's assume it's the former since you'd probably be having other errors too if the cause were to be the latter.

ISSCALAR simply checks whether the operand is a 1x1 matrix. You can replace isscalar(x) with (numel(x) == 1) OR (prod(size(x)) == 1)

HTH,
Ashish

Comment only
27 Oct 2009 maney

maney (view profile)

Hi Ashish,
I ran your code and I am getting the following error:

??? Undefined function or variable 'isscalar'.

please advise,
Thanks - maney

Comment only
24 Aug 2009 vadim

vadim (view profile)

Great job!

Comment only
24 Aug 2009 vadim

vadim (view profile)

 
Updates
28 Apr 2009 1.1

Corrected typo in an error message
Added igonoreWSpace option

18 Aug 2011 1.4

Replaced calls to str2num with str2double, the former uses eval leading to unwanted side effects if cells contain text with function names

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