I want the user to input the coordinates of 4 points such as (xa,ya),(xb,yb),(xc,yc),(xd,yd) but all of it at once. I used this code:
xa=input("Enter x-coordinate for node 1:")
ya=input("Enter y-coordinate for node 1:")
xb=input("Enter x-coordinate for node 2:")
yb=input("Enter y-coordinate for node 2:")
xc=input("Enter x-coordinate for node 3:")
yc=input("Enter y-coordinate for node 3:")
xd=input("Enter x-coordinate for node 4:")
yd=input("Enter y-coordinate for node 4:")
but in this case I am able to give input value for yd only.
How can I make the user input all the values at once?
You can take the input as a string and parse it using strsplit and evstr. Here is a simple example, taking some numbers and returning their sum.
str = input("Enter a space-separated list of numbers: ", "string")
v = evstr(strsplit(str, " "))
disp(sum(v), "The sum:")
In your case, the input may contain parentheses, commas and spaces, so it's split by a regular expression: /[ ,;()]+/ meaning any sequence of spaces, parentheses, commas and semicolons (just in case). The user might make a mistake entering data, so a basic check is implemented: the result should have 8 numbers.
need_input = %t
while need_input
str = input("Enter four pairs of coordinates: ", "string")
v = evstr(strsplit(str, "/[ ,;()]+/"))
need_input = (length(v) <> 8)
end
coords = matrix(v, 2, 4)
Entering (2,4), (-3, 4), (-9,5), (0, 1) will result in coords matrix being
2. - 3. - 9. 0.
4. 4. 5. 1.
You can also use the mscanf function
mprintf("Enter four pairs of coordinates: \n")
coords=mscanf("%f %f %f %f %f %f %f %f")
User must enter 8 values separated by space
or simply with input
str = input("Enter four pairs of coordinates: ", "string")
coords=evstr("["+str+"]")
User must enter 8 values separated by space
Related
I would like to separate each element in the matrix below with a comma.
1 2 3
4 5 6
7 8 9
Here's my attempt:
s= sprintf('%.17g,',matrix)
Ouput=1,2,3,4,5,6,7,8,9,
Desired output:
1, 2, 3
4, 5, 6
7, 8, 9
Thanks in advance for your suggestions.
You just need to specify the formatting of the entire first line:
s = sprintf('%.17g, %.17g, %.17g\n',matrix.')
MATLAB keeps re-using the formatting string as long as there are elements left in matrix.
To generalize this process, use the following expression:
s = sprintf([strjoin(repmat({'%.17g'},1,size(matrix,2)), ', ') '\n'], matrix.')
So there's a lot going on in this one line - let's unpack it from inside out:
repmat({'%.17g'},1,size(matrix,2))
This sub-expression takes a single cell array of size 1x1, containing the string %.17g, and duplicates it into a cell array with dimensions specified by the next two arguments. We want to construct a cell array with a single row (hence the argument 1) representing all the format specifiers (%...) we need. Since we want one instance of %.17g for each column, we use size(matrix,2) as the last argument to repmat, since that returns the number of columns of the matrix.
As an example, if you have 5 columns, you get this:
>> repmat({'%.17g'},1,5)
ans =
'%.17g' '%.17g' '%.17g' '%.17g' '%.17g'
Next, since you want columns delimited by commas and spaces, you can use strjoin():
>> strjoin(repmat({'%.17g'},1,5), ', ')
ans =
%.17g, %.17g, %.17g, %.17g, %.17g
Note the use of a comma and several spaces as the second argument (the delimiting string) to strjoin(). Adjust the number of spaces according to your display needs. We need one more thing to be able to print a multi-line matrix - a carriage return. To do this, we use the fact that two strings in square brackets [] are concatenated by MATLAB:
[strjoin(repmat({'%.17g'},1,size(matrix,2)), ', ') '\n']
This produces the final formatting string that we need. All that is left, is to add the sprintf and pass in the matrix argument. As Rijul Sudhir pointed out, you do have to transpose your matrix because MATLAB will walk down a column to pair the matrix elements with the format specifiers.
EDIT: Stewie Griffin was correct about the transpose operation (.') - code has been corrected.
I am working on a program for class and we need to read in a 4-bit input (e.x. 1101) from a user and treat is as a 4-bit digital data. We then need to plot this input data and use it later to calculate the Cyclic Code base on a generator polynomial we are given.
However, after looking into MATLAB input, I'm not sure how to read in the users input as a "binary input", what would be the best way to accomplish this?
Thank you!
Here is the exact part of the instructions I am having trouble with:
Ask the user for a 4-bit input digital data and plot the user given digital data
We then use that input to do the following, which I think I should be able to do once I figure out how to get the user input!
Using the polynomial P(X) = 1 + X + X3, generate the valid codeword and transmit
the codeword
You can use the input function to ask the user to insert the digit.
b4_in = input('Insert 4-bit input: ' ,'s');
The "0" "1" sequence is stored in the output variable b4_in as a string.
In MatLab binary numbers are actually string of char; you can use, for example, bin2dec to convert binary number string to decimal number).
Then you can make some check on the input validy:
length must be equal to 4
the string must contain only "0" and "1" (you can use regexp.
The whole code could be:
% Prompt for User input
b4_in = input('Insert 4-bit input: ' ,'s');
% Get the number of input digit
n_c=length(b4_in);
% Check the number of input digit
if(n_c < 4)
disp([num2str(n_c) ': Not enough input digit. 4 digits are required'])
elseif(n_c > 4)
disp([num2str(n_c) ': Too many input digit. 4 digits are required'])
else
% Check if all the input digit are valid
inv_c=regexp(b4_in,'[a-z_A-Z2-9]');
if(~isempty(inv_c))
disp(['Invalid char: ' b4_in(inv_c) ' idx= ' num2str(inv_c)])
else
% Valid input: 4 digit, only "0" or "1"
disp([b4_in ' Valid input'])
end
end
Hope this helps.
Qapla'
I have a text file which has the contents as follows.. I need to read this file column wise (ies, 2 columns here). I have tried many ways.. but cannot do as it contains "(" , "," , ")" etc... please guide..
(-2.714141687294326, 0.17700122506478025)
(-2.8889905690592976, 0.1449494260855578)
(-2.74534285564141, 0.3182989792519164)
(-2.728716536554531, -0.3267545129349194)
(-2.280859632844493, -0.7413304490629143)
(-2.8205377507406095, 0.08946138452856946)
(-2.6261449731466335, -0.16338495969832847)
(-2.8863827317805537, 0.5783117541867042)
(-2.6727557978209546, 0.11377424587411682)
(-2.5069470906518565, -0.6450688986485736)
(-2.6127552309087236, -0.01472993916137419)
(-2.7861092661880185, 0.23511200020171835)
(-3.2238037438656533, 0.5113945870063824)
(-2.6447503899420304, -1.1787646364375748)
Try this:
x = importdata('filename.txt');
x = regexp(x,'-?\d+\.?\d*','match'); %// detect numbers as [-]a[.][bcd]
x = cellfun(#str2num, vertcat(x{:}));
If the file can contain numbers in decimal form ("1.234") and in scientific notation ("1.234e-56"):
x = importdata('filename.txt');
x = regexp(x,'-?\d+\.?\d*(e-?\d+)?','match');
x = cellfun(#str2num, vertcat(x{:}));
You can use fscanf and specify the desired format:
fid = fopen('filename.txt');
x = fscanf(fid,'(%f, %f)\n',[2,inf]).';
fclose(fid);
The format spec '(%f, %f)\n' reads to float values inside brackets, separated by , per line. With [2,inf] you specify to put it into a 2 x n array, where n is as large as needed. To have the same format as before, you'll have to transpose it again .'.
Hello I have these two vectors
Q = [1,2,3,4,1,2,3,4,1,2,3,4,1,2,3,4,1,2,3,4,1,2,3,4]
and
Year = [2000,2000,2000,2000,2001,2001,2001,2001,2002.....]
and I would like to concatenate them into one single array Time
Time = [20001,20002,20003,20004,20010....]
Or
Time= {'2000Q1', '2000Q2', '2000Q3', '2000Q4', '2001Q1'....}
So far I tried with this code
m = zeros(136,1)
for i=1:136
m(i,1)= strcat(Q(i),Year(i));
end
And Matlab outputed me this:
Subscripted assignment dimension mismatch.
Help pls ?
If your vectors Year and Q have the same number of elements, you do not need a loop, just transpose them (or just make sure they are in column), then concatenate with the [] operator:
Time = [ num2str(Year.') num2str(Q.') ] ;
will give you:
20001
20002
20003
20004
20011
...
And if you want the 'Q' character, insert it in the expression:
Time = [ num2str(Year.') repmat('Q',length(Q),1) num2str(Q.') ]
Will give you:
2000Q1
2000Q2
2000Q3
2000Q4
2001Q1
...
This will be a char array, if you want a cell array, use cellstr on the same expression:
time = cellstr( [num2str(Year.') repmat('Q',length(Q),1) num2str(Q.')] ) ;
To obtain strings:
strtrim(mat2cell(num2str([Year(:) Q(:) ],'%i%i'), ones(1,numel(Q))));
Explanation:
Concat both numeric vectors as two columns (using [...])
Convert to char array, where each row is the concatenation of two numbers (using num2str with sprintf-like format specifiers). It is assumed that all numbers are integers (if not, change the format specifiers). This may introduce unwanted spaces if not all the concatenated numbers have the same number of digits.
Convert to a cell array, putting each row in a different cell (using mat2cell).
Remove whitespaces in each cell (using strtrim)
To obtain numbers: apply str2double to the above:
str2double(strtrim(mat2cell(num2str([Year(:) Q(:) ],'%i%i'), ones(1,numel(Q)))));
Or compute directly
10.^ceil(max(log10(Q)))*Year + Q;
You can use arrayfun
If you want your output in string format (with a 'Q' in the middle) then use sprintf to format the string
Time = arrayfun( #(y,q) sprintf('%dQ%d', y, q ), Year, Q, 'uni', 0 );
Resulting with a cellarray
Time =
'2000Q1' '2000Q2' '2000Q3' '2000Q4' '2001Q1' '2001Q2' '2001Q3'...
Alternatively, if you skip the 'Q' you can save each number in an array
Time = arrayfun( #(y,q) y*10+q, Year, Q )
Resulting with a regular array
Time =
20001 20002 20003 20004 20011 20012 20013 ...
Thats because you are initializing m to zeros(136,1) and then trying to save a full string into the first value. and obviously a double cannot hold a string.
I give you 2 options, but I favor the first one.
1.- you can just use cell arrays, so your code converts into:
m = cell(136,1)
for ii=1:136
m{ii}= strcat(Q(ii),Year(ii));
end
and then m will be: m{1}='2000Q1';
2.- Or if you know that your strings will ALWAYS be the same size (in your case it lokos like they are always 6) you can:
m = zeros(136,strsize)
for ii=1:136
m(ii,:)= strcat(Q(ii),Year(ii));
end
and then m will be: m(1,:)= [ 50 48 48 48 81 49 ] wich translated do ASCII will be 2000Q1
Could someone please tell me how to convert character array into a formatted output using Matlab?
I am expecting data like this:
CHAR (1 x 29) : 0.050822999 3.141592979 ; (1)
OR
CELL (1 x 1) or string: '0.050822999 3.141592979 ; (1)'
I am looking for output like this:
d1 = 0.050822999; %double
d2 = 3.141592979; %double
index = 1; % integer
I tried transposing and then using str2num(Str'); but, it's returning me 0x 0 double.
Any help would be appreciated.
Regards,
DK
you can use regexp to parse the string
c = { '0.050822999 3.141592979 ; (1)' };
p = regexp( c{1}, '^(\d+\.\d+)\s(\d+\.\d+)\s*;\s*\((\d+)\)$', 'tokens', 'once' ); %//parse the input string
numbers = str2mat(p); %// convert extracted strings to numerical values
Example result
ans =
0.050822999
3.141592979
1
Explaining the regexp pattern:
^ - pattern starts at the beginning of the input string
(\d+\.\d+) - parentheses ('()') enclosing this sub-pattern indicates it as a single token
\d+ matches one or more digits, then expecting \. a dot (notice the \, since . alone in regexp acts as a wildcard) and after the dot \d+ one or more digits are expected.
This token should correspond to the first number, e.g., 0.050822999
\s expecting a single space
(\d+\.\d+) - again, expecting another decimal fraction as the second token.
\s* - expecting white space (zero or more).
; - capture the ; in the expression, but not as a token.
\s+ - expecting white space (zero or more).
\( - expecting an open parenthesis, note the \ since parentheses in regexp are used to denote tokens.
(\d+) - expecting one or more digits as the third token, only integer numbers are expected here. no decimal point.
\) - expecting a closing parenthesis.
$ - pattern should reach the end of the input string.
You can use something like this (if I understood you correctly)
function str_dump(var)
info = whos;
disp([info.class ' ' mat2str(info.size) ' : ' var]);
end
This just shows information about the string. If you want to parse it and convert to another Matlab's structure, you have to explain it more carefully.
%// Input
a = [0.050822999 3.141592979];
n = 1;
%// Output
str = [num2str(a,'%0.9f ') ' ; (' num2str(n) ')']
Result:
str =
0.050822999 3.141592979 ; (1)