Read text file, identify variables and rewrite some of the variables

Hello.

I have a text file with its contents as shown below

A5Q00 0.30000000E+00 PMA: A, X, Y_i, Z 0.10000000E-16 0.10000000E-16 0.10000000E-16 0.30000000E+00

0.1045720000000E+08 0.1000000000000E-79 0.3500000000000E-01 0.2665390000000E+00

A5Q01 0.30000000E+00 PMB: P, X, B_i, T 0.10000000E-16 0.10000000E-16 0.10000000E-16 0.30000000E+00

0.1045720000000E+08 0.1000000000000E-79 0.3500000000000E-01 0.2665390000000E+00

A5Q02 0.30000000E+00 PMD: K, X, R_i, T 0.10000000E-16 0.10000000E-16 0.10000000E-16 0.30000000E+00

0.1045720000000E+08 0.1000000000000E-79 0.3500000000000E-01 0.2665390000000E+00

i want to store these variables V1, V2, V3...V15 for each element and change their values and again write these back to a .txt file.

I have tried using split string and storing these in the cells but i have failed ot write these cells to a text file.

clc

clear all

close all

fid =fopen('Initial.txt','r')

tline = fgetl(fid);

k = 1;

while ischar(tline)

%// Store in a cell array

A{k}=strsplit(tline," ")

tline = fgetl(fid);

k = k+1;

end

V1=A{1,1}{:,1}

V2=A{1,1}{:,2}

V3=A{1,1}{:,3}

V4=A{1,1}{:,4}

V5=A{1,1}{:,5}

V6=A{1,1}{:,6}

V7=A{1,1}{:,7}

Answer 1

[Voss]

% read the file into a char vector:
fid = fopen('Initial.txt');
data = fread(fid,'*char').';
fclose(fid);
disp(data);

A5Q00           0.30000000E+00  Aqu: P,     X_m_A, X_i_A, T             0.10000000E-16 0.10000000E-16 0.10000000E-16 0.30000000E+00
 0.1045720000000E+08 0.1000000000000E-79 0.3500000000000E-01 0.2665390000000E+00
A5Q01           0.30000000E+00  Aqu: P,     X_m_A, X_i_A, T             0.10000000E-16 0.10000000E-16 0.10000000E-16 0.30000000E+00
 0.1045720000000E+08 0.1000000000000E-79 0.3500000000000E-01 0.2665390000000E+00
A5Q02           0.30000000E+00  Aqu: P,     X_m_A, X_i_A, T             0.10000000E-16 0.10000000E-16 0.10000000E-16 0.30000000E+00
 0.1045720000000E+08 0.1000000000000E-79 0.3500000000000E-01 0.2665390000000E+00

% split into a cell array, reshape:
V = reshape(strsplit(data),15,[])

V = 15×3 cell array
    {'A5Q00'              }    {'A5Q01'              }    {'A5Q02'              }
    {'0.30000000E+00'     }    {'0.30000000E+00'     }    {'0.30000000E+00'     }
    {'Aqu:'               }    {'Aqu:'               }    {'Aqu:'               }
    {'P,'                 }    {'P,'                 }    {'P,'                 }
    {'X_m_A,'             }    {'X_m_A,'             }    {'X_m_A,'             }
    {'X_i_A,'             }    {'X_i_A,'             }    {'X_i_A,'             }
    {'T'                  }    {'T'                  }    {'T'                  }
    {'0.10000000E-16'     }    {'0.10000000E-16'     }    {'0.10000000E-16'     }
    {'0.10000000E-16'     }    {'0.10000000E-16'     }    {'0.10000000E-16'     }
    {'0.10000000E-16'     }    {'0.10000000E-16'     }    {'0.10000000E-16'     }
    {'0.30000000E+00'     }    {'0.30000000E+00'     }    {'0.30000000E+00'     }
    {'0.1045720000000E+08'}    {'0.1045720000000E+08'}    {'0.1045720000000E+08'}
    {'0.1000000000000E-79'}    {'0.1000000000000E-79'}    {'0.1000000000000E-79'}
    {'0.3500000000000E-01'}    {'0.3500000000000E-01'}    {'0.3500000000000E-01'}
    {'0.2665390000000E+00'}    {'0.2665390000000E+00'}    {'0.2665390000000E+00'}

% convert to numbers, where possible:
temp = str2double(V);
is_number = ~isnan(temp);
V(is_number) = num2cell(temp(is_number))

V = 15×3 cell array
    {'A5Q00'     }    {'A5Q01'     }    {'A5Q02'     }
    {[    0.3000]}    {[    0.3000]}    {[    0.3000]}
    {'Aqu:'      }    {'Aqu:'      }    {'Aqu:'      }
    {'P,'        }    {'P,'        }    {'P,'        }
    {'X_m_A,'    }    {'X_m_A,'    }    {'X_m_A,'    }
    {'X_i_A,'    }    {'X_i_A,'    }    {'X_i_A,'    }
    {'T'         }    {'T'         }    {'T'         }
    {[1.0000e-17]}    {[1.0000e-17]}    {[1.0000e-17]}
    {[1.0000e-17]}    {[1.0000e-17]}    {[1.0000e-17]}
    {[1.0000e-17]}    {[1.0000e-17]}    {[1.0000e-17]}
    {[    0.3000]}    {[    0.3000]}    {[    0.3000]}
    {[  10457200]}    {[  10457200]}    {[  10457200]}
    {[1.0000e-80]}    {[1.0000e-80]}    {[1.0000e-80]}
    {[    0.0350]}    {[    0.0350]}    {[    0.0350]}
    {[    0.2665]}    {[    0.2665]}    {[    0.2665]}

% ...
% make modifications to V, as desired
% ...
V{2,2} = 0.7 % (for example)

V = 15×3 cell array
    {'A5Q00'     }    {'A5Q01'     }    {'A5Q02'     }
    {[    0.3000]}    {[    0.7000]}    {[    0.3000]}
    {'Aqu:'      }    {'Aqu:'      }    {'Aqu:'      }
    {'P,'        }    {'P,'        }    {'P,'        }
    {'X_m_A,'    }    {'X_m_A,'    }    {'X_m_A,'    }
    {'X_i_A,'    }    {'X_i_A,'    }    {'X_i_A,'    }
    {'T'         }    {'T'         }    {'T'         }
    {[1.0000e-17]}    {[1.0000e-17]}    {[1.0000e-17]}
    {[1.0000e-17]}    {[1.0000e-17]}    {[1.0000e-17]}
    {[1.0000e-17]}    {[1.0000e-17]}    {[1.0000e-17]}
    {[    0.3000]}    {[    0.3000]}    {[    0.3000]}
    {[  10457200]}    {[  10457200]}    {[  10457200]}
    {[1.0000e-80]}    {[1.0000e-80]}    {[1.0000e-80]}
    {[    0.0350]}    {[    0.0350]}    {[    0.0350]}
    {[    0.2665]}    {[    0.2665]}    {[    0.2665]}

% write a new file with the modified V:
fid = fopen('Modified.txt','w');
fprintf(fid,'%-15s %14.8E  %-s %-s %10s %6s %-13s %14.8E %14.8E %14.8E %14.8E\n %19.13E %19.13E %19.13E %19.13E\n',V{:});
fclose(fid);

% view the new file's contents:
type Modified.txt

A5Q00           3.00000000E-01  Aqu: P,     X_m_A, X_i_A, T             1.00000000E-17 1.00000000E-17 1.00000000E-17 3.00000000E-01
 1.0457200000000E+07 1.0000000000000E-80 3.5000000000000E-02 2.6653900000000E-01
A5Q01           7.00000000E-01  Aqu: P,     X_m_A, X_i_A, T             1.00000000E-17 1.00000000E-17 1.00000000E-17 3.00000000E-01
 1.0457200000000E+07 1.0000000000000E-80 3.5000000000000E-02 2.6653900000000E-01
A5Q02           3.00000000E-01  Aqu: P,     X_m_A, X_i_A, T             1.00000000E-17 1.00000000E-17 1.00000000E-17 3.00000000E-01
 1.0457200000000E+07 1.0000000000000E-80 3.5000000000000E-02 2.6653900000000E-01

Instead of having numerous sequentially-numbered variables (V1, V2, V3, etc.) it's better to have a single variable that you can index (V(1), V(2), V(3), ..., or V{1}, V{2}, V{3}, ..., or V(1,:), V(2,:), V(3,:), ..., etc.)

[shadman khan]

Oh Voss....I sincerely appreciate the flawless application of algorithm to reach the ultimate goal. Couldn't have asked for more.

Thanks a ton!!

[shadman khan]

My only question where can i get the info to learn

'%-15s %14.8E %-s %-s %10s %6s %-13s %14.8E %14.8E %14.8E %14.8E\n %19.13E %19.13E %19.13E %19.13E\n'

I understand a few and missed a few

[Voss]

You're welcome!

Here's a description of those format specifiers for fprintf: https://www.mathworks.com/help/matlab/ref/fprintf.html#btf8xsy-1_sep_shared-formatSpec

[shadman khan]

Hi Voss... The code provided by you works perfectly if V1 as shown in intial pic description is a name without space.

I have run into a problem due to the "V-1" as shown in intial pic description undergoes format change such as a space in the name. This leads to its splitting when splitstr function is applied.

Hence two problem arise: 1. V-1 gets disirbuted in different cell and rshaping does not work, and even if it does, the variable-1 i.e, v1 has a wrong value.

Please see pic below

[Voss]

Hi @shadman khan, I am unable to look into this in detail at the moment, so you may want to open a new question about this issue with the space in the parameter name, and link back to this question/thread.

[shadman khan]

Dear @Voss

here's th link o the new question. I hope you can take a look when you are available: https://in.mathworks.com/matlabcentral/answers/1871827-read-text-file-identify-variables-combine-some-the-variables-and-write-these-variables-to-another

Answer 2

[Steven Lord]

I'd probably read this into a table array. A first pass at reading in this file is below. You probably want to customize the import options (perhaps using the Import Tool, uiimport, to allow you to interactively explore the effect of different options.)

thefile = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1212458/Initial.txt';

The file seems to be space delimited, but let's treat multiple spaces as one delimiter.

importOptions = detectImportOptions(thefile, 'Delimiter', ' ', ...
                                             'ConsecutiveDelimitersRule', 'join');

By default readtable takes the first row as the list of variable names, but the first row of your file is data. So let's specify some default names and say to read all the lines as data.

importOptions.VariableNames = "Var" + (1:numel(importOptions.VariableNames));
importOptions.DataLines = [1 Inf];

Now actually import the data.

T = readtable(thefile, importOptions)

T = 6×11 table
       Var1          Var2       Var3     Var4      Var5         Var6          Var7       Var8     Var9     Var10    Var11
    __________    __________    _____    _____    _______    __________    __________    _____    _____    _____    _____

    {'A5Q00' }           0.3      NaN      NaN        NaN    {'X_i_A,'}    {'T'     }    1e-17    1e-17    1e-17     0.3 
    {0×0 char}    1.0457e+07    1e-80    0.035    0.26654    {0×0 char}    {0×0 char}      NaN      NaN      NaN     NaN 
    {'A5Q01' }           0.3      NaN      NaN        NaN    {'X_i_A,'}    {'T'     }    1e-17    1e-17    1e-17     0.3 
    {0×0 char}    1.0457e+07    1e-80    0.035    0.26654    {0×0 char}    {0×0 char}      NaN      NaN      NaN     NaN 
    {'A5Q02' }           0.3      NaN      NaN        NaN    {'X_i_A,'}    {'T'     }    1e-17    1e-17    1e-17     0.3 
    {0×0 char}    1.0457e+07    1e-80    0.035    0.26654    {0×0 char}    {0×0 char}      NaN      NaN      NaN     NaN 

[shadman khan]

Hi Steven thanks for your reply. I like the compact code, but its not providing the few variables like Var3, Var4, etc.,