I currently have an instrument that sends 4 bytes representing a floating point number of 32-bit in little endian format, the data looks like:
Gz*=
<«�=
N×e=
or this
à|ƒ=
is there a conversion for this in matlab, Agilent vee and manually
To convert an array of char to single, you can use typecast:
c = 'Gz*=';
f = typecast(c, 'single')
f = 0.041621
Just implicitly!
>> data = ['Gz*=';'<«�=';'N×e=']
data =
Gz*=
<«�=
N×e=
>> data+0
ans =
71 122 42 61
60 171 65533 61
78 215 101 61
data+0 forces it to be interpreted as a number which is fine.
If it's interpreted it backwards (I'm not sure if MATLAB is big or little endian) just use the swapbytes function.
Related
Is default '\n' Matlab line terminator can be changed? Can I use ',' instead of '\n'? Because the serial port that will be reading it is programmed to terminate when ',' is read.Is it possible?
Any answers are highly appreciated! Thanks in advance!
use eg:
ser = serial('COM1'); % establish connection between Matlab and COM1
set(ser, 'Terminator', 'CR'); % set communication string to end on ASCII 13
and replace 'CR' with ','
See
http://www.swarthmore.edu/NatSci/ceverba1/Class/e5/E5MatlabExamples.html
http://www.mathworks.co.uk/help/matlab/matlab_external/terminator.html
A simple string in matlab is not terminated by \n or \0 since it is a simple array of chars, as seen here:
>> a = string('Hello World')
Warning: string is obsolete and will be discontinued.
Use char instead.
a =
Hello World
>> double(a)
ans =
72 101 108 108 111 32 87 111 114 108 100
to add a \0 to the end simply use:
>> a(end+1)=0;
>> a
a =
Hello World
>> double(a) %the zero is there, but not printable as seen here
ans =
72 101 108 108 111 32 87 111 114 108 100 0
Does anyone of you have a clue of why the following code is crashing with Index exceeds matrix dimensions. error for N_SUBJ = 17 or N_SUBJ = 14, but not for example for the values 13,15,16?
N_PICS = 7
COLR = hsv;
N_COLR = size(COLR,1);
COLR = COLR(1+[0:(N_PICS-1)]*round(N_COLR/N_PICS),:);
SUBJ_COLR = hsv;
N_SUBJ_COLR = size(SUBJ_COLR,1);
SUBJ_COLR = SUBJ_COLR(1+[0:(N_SUBJ-1)]*round(N_SUBJ_COLR/N_SUBJ),:);
And also, could somebody please explain me what it's doing exactly and how it's working?
When you say crashing, I assume you mean you are seeing the error, Index exceeds matrix dimensions.? If you are seeing this error then the matrix returned by hsv does not have enough rows for the sub-sample operation you are doing.
SUBJ_COLR = SUBJ_COLR(1+[0:(N_SUBJ-1)]*round(N_SUBJ_COLR/N_SUBJ),:);
selects a subset of the original matrix. 1+[0:(N_SUBJ-1)]*round(N_SUBJ_COLR/N_SUBJ) calculates which row to select, and : means all columns.
The matrix SUBJ_COLR is 64-by-3, thus N_SUBJ_COLR is equal to 64. You're indexing into the 64 rows of SUBJ_COLR and in some cases the particular index is greater than the number of row, resulting in a Index exceeds matrix dimensions. error. So the question is really why does this snippet
1+[0:(N_SUBJ-1)]*round(N_SUBJ_COLR/N_SUBJ)
evaluate to numbers greater than 64 for some values of N_SUBJ? This expression can be rewritten as:
1+(0:round(64/N_SUBJ):round(64/N_SUBJ)*(N_SUBJ-1))
or
1:round(64/N_SUBJ):round(64/N_SUBJ)*(N_SUBJ-1)+1
where I've replaced N_SUBJ_COLR by 64 for clarity. This latter expression more clearly shows what the largest index in the vector will be and how it depends on the value of N_SUBJ. You can print out this largest index as a function of N_SUBJ:
N_SUBJ = 1:30;
round(64./N_SUBJ).*(N_SUBJ-1)+1
which returns
ans =
Columns 1 through 13
1 33 43 49 53 56 55 57 57 55 61 56 61
Columns 14 through 26
66 57 61 65 69 55 58 61 64 67 70 73 51
Columns 27 through 30
53 55 57 59
As you can see, there are several values that exceed 64. This nonlinear behavior comes down to the use of round. The integers created by the round part don't appear to get small enough fast enough as they multiply (N_SUBJ-1) which is growing in order to keep the total term less than 64. One option might be to replace round with floor, but there are probably other ways.
Firstly it is a very simple example:
In a text file ('test1.txt'), the content is:
Formally, the
What I want to get is an array with the ASCII encoding result like:
dat_ascii = [70 111 114 109 97 108 108 121 44 32 116 104 101]
In the result, every char is translated to ASCII code, even space and common.
Now I have a text file like 10MB full with English text. I want to read it and translate every char to ASCII code and put them into a matrix (with every 4096 char per line, many lines).
How can I do this in Matlab?
You can easily convert every thing in ASCII with :
double, you just cast to double your string.
And to revert it, just do char
Example :
myStr = 'I have 2 apple.'
myStr =
I have 2 apple.
myASCII = double(myStr)
myASCII =
73 32 104 97 118 101 32 50 32 97 112 112 108 101 46
myChar = char(myASCII)
myChar =
I have 2 apple.
In order to read text file in MATLAB, you need to open the text file and read
>> filePtr = fopen('test1.txt')
and then use the file pointer to read the data and convert to ASCII values:
>> ASCIIValues = double(textscan(filePtr, '%c')); ASCIIValues{:}
Note: Use the appropriate formatting argument when you try to read a text file. In my case, I neglect all whitespaces. For documentation, read http://www.mathworks.com/help/matlab/ref/textscan.html
I know how to check an 8-neighbourhood in matlab (i.e; nlfilter). But, I want to assign the value which is more repeated to the center value. So, say for instance that I have the following values in the 8-neighbourhood:
2-values = 56
3-values = 64
1-value = 70
1-value = 87
1-value = 65
In this case we would assign 64 to the center pixel.
How can we do that?
Thanks.
I think you want either the mode or the histc function.
M=mode(X) for vector X computes M as the sample mode, or most
frequently
occurring value in X.
Example with your data:
x = [56 56 64 64 64 70 87 65];
mode(x)
ans =
64
But this will only get you the most frequently occurring value.
If you want the count of each unique item in the array, you could do,
unqx = unique(x);
unqx =
56 64 65 70 87
valueCount = histc(x, unqx)
ans =
2 3 1 1 1
You could then sort this and take the first N values
valueCount = sort(valueCount, 'descend');
% Use unqx(valueCount(1:N))
from MATLAB command line , when I type my variable a , it gives me values as expected :
a =
value_1
value_2
and I would like to access to each value of a, I tried a(1) but this gives me empty
the type of a is 1x49char.
how could I get value_1 and value_2 ?
whos('a')
Name Size Bytes Class Attributes
a 1x49 98 char
I get the a from xml file :
<flag ="value">
<flow>toto</flow>
<flow>titi</flow>
</flag>
a+0:
ans =
10 32 32 32 32 32 32 32 32 32 32 32 32 98,...
111 111 108 101 97 110 95 84 10 32 32 32 32 32,...
32 32 32 32 32 32 32 66 79 79 76 10 32 32,...
32 32 32 32 32 32 32
Perhaps a is a string with a newline in it. To make two separate variables, try:
values = strtrim(strread(a, '%s', 'delimiter', sprintf('\n')))
strread will split a into separate lines, and strtrim will remove leading/trailing whitespace.
Then you can access the lines using
values{1}
values{2}
(note that you must use curly brackets since this is a cell array of strings).
How are you reading in the xml file? If you're using xmlread then MatLab adds a lot of white space in there for you and could be the cause of your problems.
http://www.mathworks.com/matlabcentral/fileexchange/28518-xml2struct
This will put your xml file into a struct where you should be able to access the elements in the array.
You seem to have an somewhat inconvenient character array. You can convert this array in a more manageable form by doing something like what #Richante said:
strings = strread(a, '%s', 'delimiter', sprintf('\n'));
Then you can reference to toto and titi by
>> b = strings{2}
b =
toto
>> c = strings{3}
c =
titi
Note that strings{1} is empty, since a starts with a newline character. Note also that you don't need a strtrim -- that is taken care of by strread already. You can circumvent the initial newlines by doing
strings = strread(a(2:end), '%s', 'delimiter', sprintf('\n'));
but I'd only do that if the first newline is consistently there for all cases. I'd much rather do
strings = strread(a, '%s', 'delimiter', sprintf('\n'));
strings = strings(~cellfun('isempty', strings))
Finally, if you'd rather use textscan instead of strread, you need to do 1 extra step:
strings = textscan(a, '%s', 'delimiter', sprintf('\n'));
strings = [strings{1}(2:end)];