Reading Complex Text Data (MATLAB)

Text data which is in one format all through the file is easier to read. But when the text data has numeric entries, string entries (different data formats), then it becomes little complicated to read and write. Sometimes, the data is also not arranged in regular rows and columns form which makes them even more tougher to read.

Here we address such problems.

Reading complex text data

Reading Data

clear; close all; clc;

filename='stn_data.txt'; %giving the file name to be opened

fileID = fopen(filename); %defining the identifier for file

format='%s %f %f'; %format of the text file

data=textscan(fileID,format);

fclose(fileID); %close the file

stnName=data{1};    %reading the first column

data1=data{2};  %reading the second column

data2=data{3};  %reading the third column

Writing Data:

clear; close all; clc;

%% Writing Data into the text file

%defining a number of strings

stnName={'ABC','DEF','GHI','JKL','MNO','PQR','STU','VWX','YZA'}; 

%defining variable data1 with values between 0-10

data1=10*rand(1,length(stnName));

%defining variable data1 with values between 0-100

data2=100*rand(1,length(stnName));

fileid=fopen('stn_data.txt','w'); %opening a file in writing mode

for i=1:length(stnName)

    fprintf(fileid,'%s %.3f %.3f\n',stnName{i},data1(i),data2(i)); %writing data into the file iteratively

end

fclose(fileid); % closing the file

MATLAB Scripts:

Reading data

Writing data

Using a Function (MATLAB)

If we need to run the same algorithms or formula for computations again and again, then instead of writing the same stuffs in our script file many times, we can simply write a function. This makes our script look simpler and faster to run.

Writing a function in MATLAB

Examples:

Calculating mean and standard deviation

Calculating distance from origin

Calculates distance (in km) between two coordinate points on the Earth’s surface

Writing and Reading Simple Text Data (MATLAB)

Working with text data is convenient as we can share our data with other systems without giving them the trouble to install a particular software to read our data.

Let’s see how we can read and write a text data using MATLAB.

Reading text data in MATLAB

Reading text Data

%% Reading the data in text file

fileID = fopen('nums.txt','r'); %opeing the file in reading mode

p=fscanf(fileID,'%s %s',2); %reads the header

formatSpec = '%d %f'; %defining the format of the data

sizeA = [2 Inf]; %defining the size of the data

A = fscanf(fileID,formatSpec,sizeA); %reading the data using fscanf function

fclose(fileID); %closing the file

A' %displaying the data

Writing Text Data

clear; close all; clc;

%% Defining the variables

x = 1:10;

y = [x;10*rand(1,10)]; %randomly generated 2nd column

z=['x-values' '  ' 'random-values']; %writing the header

%% Writing the data in text file

fileID = fopen('nums.txt','w'); %opens a text file in writing mode

fprintf(fileID,'%s %s %s\n',z);

fprintf(fileID,'\n');

fprintf(fileID,' %d         %4.4f\n',y); %write the data y in the file. 

%The first column is written in digit format and second column in floating point format.

fclose(fileID); %close the file

MATLAB Scripts:

Reading text data

Writing text data