I am working on a C code to read in three columns of numbers from an input file and then do basic math with the numbers obtained. My input file looks like:
155.4996 38.0078 7.65
93.9968 44.9926 7.68
I am currently trying to separate columns using sscanf. To get this started I am trying to read in the columns and print just the third column to an output file. Below is what I have right now:
FILE * fp;
FILE * fp2;
char *string;
char out[2000];
char read[1000];
int column1, column2, column3;
strcpy(read, "casecent");
strcpy(out, "Diff");
fp = fopen(read, "r");
fp2 = fopen(out, "w+");
while (!feof(fp))
{
fgets(string, 1000, fp);
sscanf(string, "%d %d %d", &column1, &column2, &column3);
fprintf(fp2,"%d\n", column3);
}
I am currently getting zeros in the output file instead of numbers. I'm sure I'm just missing something small and dumb but if you could help me out it would be much appreciated.
Use float or double for the column variables' data types. Then use %f or %lf respectively in the format string for sscanf, depending on which data type you chose.
If you want to store or print the values as integers, you'll still have to read them as floats or doubles first, then convert.
Related
I have a measurement device PCE-VDL, which gives me measurements in following CSV format below, which I need to import to OCTAVE for further investigation.
Especially I need to import last 3 columns with xyz acceleration data.
The file is in CSV format with delimiter of semicolon ";".
I have tried:
A_1 = importdata ("file.csv", ";", 3);
but have recieved
error: missing_idx(10): out of bound 9
The CSV file looks like this:
#PCE-VDL X - TableView series
#2020.16.11
#Date;Time;Duration [s];t [°C];RH [%];p [mbar];aX [g];aY [g];aZ [g];
2020.28.10;16:16:32:0000;00:000;;;;0,0195;-0,0547;1,0039;
2020.28.10;16:16:32:0052;00:005;;;;0,0898;-0,0273;0,8789;
2020.28.10;16:16:32:0104;00:010;;;;0,0977;-0,0313;0,9336;
2020.28.10;16:16:32:0157;00:015;;;;0,1016;-0,0273;0,9297;
The numbers in last 3 columns have also decimal coma and not decimal point. So there probably should be done also some conversion.
Thank you very much for any help.
Regards
EDIT: 18.11.2020
Thanks for help. I have tried now following:
A_1_str = fileread ("file.csv");
A_1_str_m = strrep (A_1_str, ".", "-");
A_1_str_m = strrep (A_1_str_m, ",", ".");
save "A_1_str_m.csv" A_1_str_m;
A_1 = importdata ("A_1_str_m.csv", ";", 8);
and still receive error: file_content(140): out of bound 139
There is probably some problem with time format in first columns, which I do not want to read. I just need last three columns.
After my conversion, the file looks like this:
# Created by Octave 5.1.0, Wed Nov 18 21:40:52 2020 CET <zdenek#ASUS-F5V>
# name: A_1_str_m
# type: sq_string
# elements: 1
# length: 7849
#PCE-VDL X - TableView series
#2020-16-11
#Date;Time;Duration [s];t [°C];RH [%];p [mbar];aX [g];aY [g];aZ [g];
2020-28-10;16:16:32:0000;00:000;;;;0.0195;-0.0547;1.0039;
2020-28-10;16:16:32:0052;00:005;;;;0.0898;-0.0273;0.8789;
2020-28-10;16:16:32:0104;00:010;;;;0.0977;-0.0313;0.9336;
Thanks for support!
You can first read the data with fileread, which stores the data as a string. Then you can manipulate the string like this:
new_string = strrep(string, ",", ".");
strrep replaces all occurrences of a pattern within a string. Afterwards you save this data as a separate file or you overwrite the existing file with the manipulated data. When this is done you proceed as you have tried before.
EDIT: 19.11.2020
To avoid the additional heading lines in the new file, you can save it like this:
fid = fopen("A_1_str_m.csv", "w");
fputs(fid, A_1_str_m);
fclose(fid);
fputs will just write the string to the file.
The you can read the new file with dlmread.
A1_buf = dlmread("A_1_str_m.csv", ";");
A1_buf = real(A1); # get the real value of the complex number
A1_buf(1:3, :) = []; # remove the headlines
A1 = A1_buf(:, end-3:end-1); # get only the the 3 columns you're looking for
This will give you the three columns your looking for. But the date and time data will be ignored.
EDIT 20.11.2020
Replaced abs with real, so the sign of the value will be kept.
Use csv2cell from the io package.
I have a text file with 1 million decimal digits of "e" number with 80 digits on each line excluding the first and the last line which have 76 and 4 digits and the file has 12501 lines. I want to convert it into a vector in matlab with each digit on each row. I tried num2str function, but the problem is that it gets converted like for example '7.1828e79' (13 characters). What can I do?
P.S.1: The first two lines of the text file (76 and 80 digits) are:
7182818284590452353602874713526624977572470936999595749669676277240766303535 47594571382178525166427427466391932003059921817413596629043572900334295260595630
P.S.2: I used "dlmread" and got a 12501x1 vector, with the first and second row of 7.18281828459045e+75 and 4.75945713821785e+79 and the problem is that when I use num2str for example for the first row value, I get: '7.182818284590453e+75' as a string and not the whole 76 digits. My aim was to do something like this:
e1=dlmread('e.txt');
es1=num2str(e1);
for i=1:12501
for j=1:length(es1(1,:))
a1((i-1)*length(es1(1,:))+j)=es1(i,j);
end
end
e_digits=a1.';
but I get a string like this:
a1='7.182818284590453e+754.759457138217852e+797.381323286279435e+799.244761460668082e+796.133138458300076e+791.416928368190255e+79 5...'
with 262521 characters instead of 1 million digits.
P.S.3: I think the problem might be solved if I can manipulate the text file in a way that I have one digit on each line and simply use dlmread.
Well, this is not hard, there are many ways to do it.
So first you want to load in your file as a Char Array using something simple like (you want a Char Array so that you can easily manipulate it to forget about the lines breaks) :
C = fileread('yourfile.txt'); %loads file as Char Array
D = C(~isspace(C)); %Removes SPACES which are line-breaks
Next, you want to actually append a SPACE between each char (this is because you want to use the num2str transform - and matlab needs to see the space), you can do this using a RESHAPE, a STRTRIM or simply a REGEX:
E = strtrim(regexprep(D, '.{1}', '$0 ')); %Add a SPACE after each Numeric Digit
Now you can transform it using str2num into a Vector:
str2num(E)'; %Converts the Char Array back to Vector
which will give you a single digit each row.
Using your example, I get a vector of 156 x 1, with 1 digit each row as you required.
You can get a digit per row like this
fid = fopen('e.txt','r');
c = textscan(fid,'%s');
c=cat(1,c{:});
c = cellfun(#(x) str2num(reshape(x,[],1)),c,'un',0);
c=cat(1,c{:});
And it is not the only possible way.
Could you please tell what is the final task, how do you plan using the array of e digits?
I have the following sample from a CSV file. Structure is:
Date ,Time(Hr:Min:S:mS), Value
2015:08:20,08:20:19:123 , 0.05234
2015:08:20,08:20:19:456 , 0.06234
I then would like to read this into a matrix in MATLAB.
Attempt :
Matrix = csvread('file_name.csv');
Also tried an attempt formatting the string.
fmt = %u:%u:%u %u:%u:%u:%u %f
Matrix = csvread('file_name.csv',fmt);
The problem is when the file is read the format is wrong and displays it differently.
Any help or advice given would be greatly appreciated!
EDIT
When using #Adriaan answer the result is
2015 -11 -9
8 -17 -1
So it seems that MATLAB thinks the '-' is the delimiter(separator)
Matrix = csvread('file_name.csv',1,0);
csread does not support a format specifier. Just enter the number of header rows (I took it to be one, as per example), and number of header columns, 0.
You file, however, contains non-numeric data. Thus import it with importdata:
data = importdata('file_name.csv')
This will get you a structure, data with two fields: data.data contains the numeric data, i.e. a vector containing your value. data.textdata is a cell containing the rest of the data, you need the first two column and extract the numerics from it, i.e.
for ii = 2:size(data.textdata,1)
tmp1 = data.textdata{ii,1};
Date(ii,1) = datenum(tmp1,'YYYY:MM:DD');
tmp2 = data.textdata{ii,2};
Date(ii,2) = datenum(tmp2,'HH:MM:SS:FFF');
end
Thanks to #Excaza it turns out milliseconds are supported.
How can I turn strings like 1-14 into 01_014? (and for 2-2 into 02_002)?
I can do something like this:
testpoint_number = '5-16';
temp = textscan(testpoint_number, '%s', 'delimiter', '-');
temp = temp{1};
first_part = temp{1};
second_part = temp{2};
output_prefix = strcat('0',first_part);
parsed_testpoint_number = strcat(output_prefix, '_',second_part);
parsed_testpoint_number
But I feel this is very tedious, and I don't know how to handle the second part (16 to 016)
As you are handling integer numbers, I would suggest to change the textscan to %d (integer numbers). With that, you can use the formatting power of the *printf commands (e.g. sprintf).
*printf allows you to specify the width of the integer. With %02d, a 2 chars wide integer, which will be filled up with zeros, is printed.
The textscan returns a {1x1} cell, which contains a 2x1 array of integers. *printf can handle this itsself, so you just have to supply the argument temp{1}:
temp = textscan(testpoint_number, '%d', 'delimiter', '-');
parsed_testpoint_number = sprintf('%02d_%03d',temp{1});
Your textscanning is probably the most intuitive way to do this, but from then on what I would recommend doing is instead converting the scanned first_part and second_part into numerical format, giving you integers.
You can then sprintf these into your target string using the correct 'c'-style formatters to indicate your zero-padding prefix width, e.g.:
temp = textscan(testpoint_number, '%d', 'delimiter', '-');
parsed_testpoint_number = sprintf('%02d_%03d', temp{1});
Take a look at the C sprintf() documentation for an explanation of the string formatting options.
I had a similar question. but what i am trying now is to read files in .txt format into MATLAB. My problem is with the headers. Many times due to errors the system rewrites the headers in the middle of file and then MATLAB cannot read the file. IS there a way to skip it? I know i can skip reading some characters if i know what the character is.
here is the code i am using.
[c,pathc]=uigetfile({'*.txt'},'Select the data','V:\data');
file=[pathc c];
data= dlmread(file, ',', 1,4);
this way i let the user pick the file. My files are huge typically [ 86400 125 ]
so naturally it has 125 header fields or more depends on files.
Thanks
Because the files are so big i cannot copy , but its in format like
day time col1 col2 col3 col4 ...............................
2/3/2010 0:10 3.4 4.5 5.6 4.4 ...............................
..................................................................
..................................................................
and so on
With DLMREAD you can read only numeric data. It will not read date and time, as your first two columns contain. If other data are all numeric you can tell DLMREAD to skip first row and 2 columns on the right:
data = dlmread(file, ' ', 1,2);
To import also day and time you can use IMPORTDATA instead of DLMREAD:
A = importdata(file, ' ', 1);
dt = datenum(A.textdata(2:end,1),'mm/dd/yyyy');
tm = datenum(A.textdata(2:end,2),'HH:MM');
data = A.data;
The date and time will be converted to serial numbers. You can convert them back with DATESTR function.
It turns out that you can still use textscan. Except that you read everything as string. Then, you attempt to convert to double. 'str2double' returns NaN for strings, and since headers are all strings, you can identify header rows as rows with all NaNs.
For example:
%# find and open file
[c,pathc]=uigetfile({'*.txt'},'Select the data','V:\data');
file=[pathc c];
fid = fopen(file);
%# read all text
strData = textscan(fid,'%s%s%s%s%s%s','Delimiter',',');
%# close the file again
fclose(fid);
%# catenate, b/c textscan returns a column of cells for each column in the data
strData = cat(2,strData{:});
%# convert cols 3:6 to double
doubleData = str2double(strData(:,3:end));
%# find header rows. headerRows is a logical array
headerRowsL = all(isnan(doubleData),2);
%# since I guess you know what the headers are, you can just remove the header rows
dateAndTimeCell = strData(~headerRowsL,1:2);
dataArray = doubleData(~headerRowsL,:);
%# and you're ready to start working with your data