Keep getting an error with my function regarding textscan()

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louis beauregard 2017-2-18

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评论： louis beauregard 2017-2-19

I'm trying to import a text file as a 2 row vector and keep getting this back,

Error using textscan
Invalid file identifier. Use fopen to generate a valid file identifier.
Error in importfile (line 36)
textscan(fileID, '%[^\n\r]', startRow(1)-1, 'WhiteSpace', '', 'ReturnOnError', false);

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Answer 1

Image Analyst 2017-2-18

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When you used fopen(), it probably returned an invalid file handle, like the file doesn't exist, is locked, or is readonly. Did you check the value of fileID that fopen returned? You forgot to show us the fopen() line of code.

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louis beauregard 2017-2-18

编辑：Walter Roberson 2017-2-19

在 MATLAB Online 中打开

when we imported the data from the import data we created a function with it, and this was my code:

[t,v]=importfile('LA.txt')
%IMPORTFILE Import numeric data from a text file as column vectors.
%   [DATETIME2142017602PM,VARNAME2] = IMPORTFILE(FILENAME) Reads data from
%   text file FILENAME for the default selection.
%
%   [DATETIME2142017602PM,VARNAME2] = IMPORTFILE(FILENAME, STARTROW,
%   ENDROW) Reads data from rows STARTROW through ENDROW of text file
%   FILENAME.
%
% Example:
%   [datetime2142017602PM,VarName2] = importfile('LA',4, 10003);
%
%    See also TEXTSCAN.
% Auto-generated by MATLAB on 2017/02/18 15:59:04
%%Initialize variables.
delimiter = '\t';
if nargin<=2
    startRow = 4;
    endRow = inf;
end
%%Format for each line of text:
%   column1: double (%f)
%  column2: double (%f)
% For more information, see the TEXTSCAN documentation.
formatSpec = '%f%f%[^\n\r]';
%%Open the text file.
fileID = fopen(filename,'r');
%%Read columns of data according to the format.
% This call is based on the structure of the file used to generate this
% code. If an error occurs for a different file, try regenerating the code
% from the Import Tool.
textscan(fileID, '%[^\n\r]', startRow(1)-1, 'WhiteSpace', '', 'ReturnOnError', false);
dataArray = textscan(fileID, formatSpec, endRow(1)-startRow(1)+1, 'Delimiter', delimiter, 'EmptyValue' ,NaN,'ReturnOnError', false, 'EndOfLine', '\r\n');
for block=2:length(startRow)
    frewind(fileID);
    textscan(fileID, '%[^\n\r]', startRow(block)-1, 'WhiteSpace', '', 'ReturnOnError', false);
    dataArrayBlock = textscan(fileID, formatSpec, endRow(block)-startRow(block)+1, 'Delimiter', delimiter, 'EmptyValue' ,NaN,'ReturnOnError', false, 'EndOfLine', '\r\n');
    for col=1:length(dataArray)
        dataArray{col} = [dataArray{col};dataArrayBlock{col}];
    end
end
%%Close the text file.
fclose(fileID);
%%Post processing for unimportable data.
% No unimportable data rules were applied during the import, so no post
% processing code is included. To generate code which works for
% unimportable data, select unimportable cells in a file and regenerate the
% script.
%%Allocate imported array to column variable names
datetime2142017602PM = dataArray{:, 1};
VarName2 = dataArray{:, 2};

Walter Roberson 2017-2-19

The apparent use of IMPORTFILE was because the code was not formatted :(

Walter Roberson 2017-2-19

The file might have been present before in the current directory, but that does not mean that it is present now in any directory, let alone the current directory.

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Answer 2

louis beauregard 2017-2-19

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the fileId is -1

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Walter Roberson 2017-2-19

在 MATLAB Online 中打开

Change the line

fileID = fopen(filename,'r');

to

[fileID, msg] = fopen(filename,'r');
if fileID < 0
  error('Failed to open file "%s" because: "%s"', filename, msg);
end

louis beauregard 2017-2-19

lol i ended up going into the file directory and changing them to .txt and it worked but thanks for the help

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Keep getting an error with my function regarding textscan()

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Keep getting an error with my function regarding textscan()

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