ERROR unable to convert 'string' value to 'int64'

So I am trying to extract data from a .txt file in which the name is provided by the user, change one column, and create a new .txt file with the same data including the alterations. I figured that much out and have managed to create the file, but I am having the hardest time getting my data to properly enter into the new file. I want four distinct columns for each of the data. This is my code below.

fileOriginal = fopen(fileName,'r');
if fileOriginal == -1
    disp('The file cannot be found')
    nameOriginal = input('Please enter the name of the ASCII text file in which data will be retrived from: ','s');
else
    C = textscan(fileOriginal,'%d %s %d %d %d','HeaderLines',1);
end

Yr = C{1};
Mnth = C{2};
LowTemp = C{3};
HighTemp = C{4};
Precip = C{5};

Yr = 1900 + Yr;
fileNew = fopen(newFileName,'w');
Mnth = string(Mnth);
T = [Yr Mnth LowTemp HighTemp Precip];

fprintf(fileNew,'%i %s %i %i %i',T);

When I try to use fprintf to insert my altered into the new file I created, I keep getting an error that says "Unable to convert 'string' value to 'int64'." although I don't understand where it is being converted to int64. Any help is appreciated.

Answer 1

[dpb]

Yr = 1900 + Yr;
fileNew = fopen(newFileName,'w');
Mnth = string(Mnth);
T = [Yr Mnth LowTemp HighTemp Precip];

You've got a number in Yr and a string in Mnth and are trying to put those together into a single vector with []. In a nutshell, "You can't DO that!"

fprintf and friends take multiple arguments...

fprintf(fileNew,'%i %s %i %i %i',Yr,Mnth,LowTemp,HighTemp,Precip);

[Hannah Lamon]

That was my original plan of attack, however when I run the code below...

Yr = 1900 + Yr;
fileNew = fopen(newFileName,'w');
Mnth = string(Mnth);

fprintf(fileNew,'%i %s %i %i %i',Yr,Mnth,LowTemp,HighTemp,Precip);

...I recieve the same 'Unable to convert 'string' value to 'int64'.' at the fprintf line.

[dpb]

We can't reproduce your code because we don't have the file...need at least the result of what

whos Yr Mnth LowTemp HighTemp Precip

returns for the bare minimum...

Wouldn't hurt to show what

which fprintf -all

returns, just in case you've somehow aliased it...

[Hannah Lamon]

This is the information stored in my original file...

Yr    Mnth   LowTemp(°F)  HighTemp(°F)  Precip(in)
89    Feb       53.8          71.6        2.67  
89    Mar       58.5          76.3        2.84       
89    Apr       62.4          80.6        1.80
89    May       68.9          86.3        2.85

When I run the whos command this is what displays...

  Name          Size            Bytes  Class     Attributes

  HighTemp      4x1                16  int32               
  LowTemp       4x1                16  int32               
  Mnth          4x1               344  string              
  Precip        4x1                16  int32               
  Yr            4x1                16  int32               

And this is what results when I run the which command...

  built-in (C:\Users\Hannah\Desktop\MATLab\toolbox\matlab\iofun\fprintf)
C:\Users\Hannah\Desktop\MATLab\toolbox\shared\instrument\@icinterface\fprintf.m  % icinterface method
C:\Users\Hannah\Desktop\MATLab\toolbox\matlab\serial\@serial\fprintf.m           % serial method

Thank you for your help!

Answer 2

[dpb]

  Name          Size            Bytes  Class     Attributes
  HighTemp      4x1                16  int32               
  LowTemp       4x1                16  int32               
  Mnth          4x1               344  string              
  Precip        4x1                16  int32               
  Yr            4x1                16  int32               

Aha! What you didn't tell us (but should have guessed) is that the variables are arrays...and you have output each _array_ in sequence, not an element from each array in turn. Consequently, the first Yr value is output to the '%i' format specifier but the next data to be output is Yr(2) and that won't fit in a string format specifier.

Remember, Matlab is vectorized and each reference to a variable that is an array or vector without subscripting returns the entire array. What you need/want is--

Yr = 1900 + Yr;
fileNew = fopen(newFileName,'w');
Mnth = string(Mnth);
fmt=['%4d %5s' repmat('%6.2f',1,3) '\n'];
for i=1:size(Yr,1);
  fprintf(fileNew,fmt,Yr(i),Mnth(i),LowTemp(i),HighTemp(i),Precip(i))
end

[Hannah Lamon]

AHH now I see my issue, thank you so much! Works great!