I'm working with sscanf to extract a number from a string. The strings are usually in the form of:
'44 ppm'
'10 gallons'
'23.4 inches'
but ocassionally they are in the form of:
'<1 ppm'
If I use the following code:
x = sscanf('1 ppm','%f')
I get an output of
1
But if I add the less than sign in front of the one:
x = sscanf('<1 ppm','%f')
I get:
[]
How can I write this code so this actually produces a number? I'm not sure yet what number it should print...but let's just say it should print 1 for the moment.
You can use regexp:
s= '<1 ppm';
x=regexp(s, '.*?(\d+(\.\d+)*)', 'tokens' )
x{1}
Demo :
>> s= {'44 ppm', '10 gallons', '23.4 inches', '<1 ppm' } ;
>> x = regexp(s, '.*?(\d+(\.\d+)*)', 'tokens' );
>> cellfun( #(x) disp(x{1}), x ) % Demo for all
'44'
'10'
'23.4'
'1'
Related
I'm writing a program that calculates the Factorial of 5 numbers and output the results in a Tabular form but I keep getting Zeros.
Factorial Formula:. n! = n×(n-1)!
I tried:
CLS
DIM arr(5) AS INTEGER
FOR x = 1 TO 5
INPUT "Enter Factors: ", n
NEXT x
f = 1
FOR i = 1 TO arr(n)
f = f * i
NEXT i
PRINT
PRINT "The factorial of input numbers are:";
PRINT
FOR x = 1 TO n
PRINT f(x)
NEXT x
END
and I'm expecting:
Numbers Factorrials
5 120
3 6
6 720
8 40320
4 24
You did some mistakes
FOR i = 1 TO arr(n)
where is n defined
you also never stored actual values into arr
PRINT f(x)
here you take from array f that is also not defined in your code
Possible solution to calculate arrays of factorials:
CLS
DIM arr(5) AS INTEGER
DIM ans(5) AS LONG
FOR x = 1 TO 5
INPUT "Enter Factors: ", arr(x)
f& = 1
FOR i = 1 TO arr(x)
f& = f& * i
NEXT i
ans(x) = f&
NEXT x
PRINT
PRINT "The factorial of input numbers are:";
PRINT
PRINT "Numbers", "Factorials"
FOR x = 1 TO 5
PRINT arr(x), ans(x)
NEXT x
END
I don't have a BASIC interpreter right in front of me, but I think this is what you're looking for:
CLS
DIM arr(5) AS INTEGER
DIM ans(5) AS LONG 'You need a separate array to store results in.
FOR x = 1 TO 5
INPUT "Enter Factors: ", arr(x)
NEXT x
FOR x = 1 to 5
f& = 1
FOR i = 1 TO arr(x)
f& = f& * i
NEXT i
ans(x) = f&
NEXT x
PRINT
PRINT "The factorial of input numbers are:";
PRINT
PRINT "Numbers", "Factorials"
FOR x = 1 TO 5
PRINT STR$(arr(x)), ans(x)
NEXT x
END
Just a comment though: In programming, you should avoid reusing variables unless you are short on memory. It can be done right, but it creates many opportunities for hard to find bugs in larger programs.
Possible solution to calculate arrays of factorials and square roots:
CLS
PRINT "Number of values";: INPUT n
DIM arr(n) AS INTEGER
DIM ans(n) AS LONG
FOR x = 1 TO n
PRINT "Enter value"; x;: INPUT arr(x)
f& = 1
FOR i = 1 TO arr(x)
f& = f& * i
NEXT i
ans(x) = f&
NEXT x
PRINT
PRINT "The factorial/square root of input numbers are:";
PRINT
PRINT "Number", "Factorial", "Squareroot"
FOR x = 1 TO n
PRINT arr(x), ans(x), SQR(arr(x))
NEXT x
END
If we have
A=[100 -0.1 0];
B=[30 0.2 -2]; t1='text 1'; t2=text 2'
how to use fprintf so that the output saved in a file will look like that
100 -1.000E-0001 0.000E-0000 'text 1'
30 2.000E-0001 -2.000E-0000 'text 2'
I put together a "one-liner" (spread across several lines for better readability) that takes an array, a single number format, and a delimiter and returns the desired string. And while you found the leading blank-space flag, I prefer the + flag, though the function will work with both:
A=[-0.1 0];
B=[0.2 -2];
minLenExp = 4;
extsprintf = #(num,fmt,delim) ...
strjoin(cellfun(...
#(toks)[toks{1},repmat('0',1,max([0,minLenExp-length(toks{2})])),toks{2}],...
regexp(sprintf(fmt,num),'([+-\s][\.\d]+[eE][+-])(\d+)','tokens'),...
'UniformOutput',false),delim);
Astr = extsprintf(A,'%+.4E',' ');
Bstr = extsprintf(B,'%+.4E',' ');
disp([Astr;Bstr]);
Running this yields:
>> foo
-1.0000E-0001 +0.0000E+0000
+2.0000E-0001 -2.0000E+0000
(foo is just what the script file is called.)
Here's a more general approach that searches for the exponential format instead of assuming it:
A=[100 -0.1 0].';
B=[30 0.2 -2];
extsprintf = #(fmt,arr) ...
regexprep(...
sprintf(fmt,arr),...
regexprep(regexp(sprintf(fmt,arr),'([+-\s][\.\d]+[eE][+-]\d+)','match'),'([\+\.])','\\$1'),...
cellfun(#(match)...
cellfun(...
#(toks)[toks{1},repmat('0',1,max([0,minLenExp-length(toks{2})])),toks{2}],...
regexp(match,'([+-\s][\.\d]+[eE][+-])(\d+)','tokens'),...
'UniformOutput',false),...
regexp(sprintf(fmt,arr),'([+-\s][\.\d]+[eE][+-]\d+)','match')));
fmt = '%3d %+.4E %+.4e';
disp(extsprintf(fmt,A));
disp(extsprintf(fmt,B));
Outputs
>> foo
100 -1.0000E-0001 +0.0000e+0000
30 +2.0000E-0001 -2.0000e+0000
I want to print the following text on a matlab figure with ':' sign vertically aligned:
Total Events: 1234
Mean Value: 1234
Standard Deviation: 1234
1st Quartile: 1234
...
...
I am using text function and trying to insert spaces manually but they never seemed to be aligned perfectly and looks wavy.
Any helps, please.
You can use a fixed-width font and use a cell array to put the text on different lines:
text( 0, 0, { ' Total Events: 1234' ...
' Mean Value: 1234' ...
'Standard Deviation: 1234' ...
' 1st Quartile: 1234' }, 'FontName', 'FixedWidth' )
Use string format
strings = {'Total Events', 'Mean Value', 'Standard Deviation', '1st Quartile'};
max_len = max( cellfun( #numel, strings ) );
fs = sprintf( '%% %ds: 1234\n', max_len );
cellfun( #(x) fprintf(1,fs,x), strings );
Results with:
Total Events: 1234
Mean Value: 1234
Standard Deviation: 1234
1st Quartile: 1234
As you can see the command that aligns to the right is
sprintf( '% 18s: 1234', strings{1} )
So, eventually in your text command, instead of explicitly writing a string, you can format one using sprintf:
text( 0, 0, sprintf( '% 18s: %d', strings{ii}, values(ii) );
Assuming you have strings - cell array of strings and same-length array values with corresponding values to print.
I have 100 ASCII files in my directory all named as follows:
int_001.ASC
int_002.ASC
int_003.ASC
.
.
.
int_099.ASC
int_100.ASC
I have to import them in MATLAB all with importdata, which should work as follows:
A = importdata('int_001.ASC', ' ', 9)
x = A.data(:,1)
y = A.data(:,2)
My question is: how can I avoid writing 100 times importdata? Is there a way to write the first string only and then have all data uploaded?
Thanks
fls = dir( 'int_*.ASC' );
for fi=1:numel(fls)
A{fi} = importdata( fls(fi).name, ' ', 9 );
% ...
end
UPDATE:
You may use string formatting to read the files according to their numbers:
for fi=1:100
A{fi} = importdata( sprintf('int_%03d.ASC', fi ), ' ', 9 );
% ...
end
You can use strcat function in a for loop :
for k=1:n
fileName = strcat('int_',num2str(k, '%03d'),'.ASC');
A(k) = importdata(fileName, ' ', 9);
x(k) = A(k).data(:,1);
y(k) = A(k).data(:,2);
end
If you want to take this a little overboard:
alldata = arrayfun(...
#(dirEntry)importdata(dirEntry.name, ' ', 9), ...
dir('int_*.ASC'),...
'uniformoutput',false);
This line does the following
Gets a listing of all files matching the partial filename, as an array of structures (h/t Shai)
For each element in that array, performs the importdata call from your original post.
Compiles all the outputs into a cell array.
Hey guys, I have a very simple problem in MATLAB:
I have some strings which are like this:
Pic001
Pic002
Pic003
004
Not every string starts with the prefix "Pic". So how can I cut off the part "pic" that only the numbers at the end shall remain to have an equal format for all my strings?
Greets, poeschlorn
If 'Pic' only ever occurs as a prefix in your strings and nowhere else within the strings then you could use STRREP to remove it like this:
>> x = {'Pic001'; 'Pic002'; 'Pic003'; '004'}
x =
'Pic001'
'Pic002'
'Pic003'
'004'
>> x = strrep(x, 'Pic', '')
x =
'001'
'002'
'003'
'004'
If 'Pic' can occur elsewhere in your strings and you only want to remove it when it occurs as a prefix then use STRNCMP to compare the first three characters of your strings:
>> x = {'Pic001'; 'Pic002'; 'Pic003'; '004'}
x =
'Pic001'
'Pic002'
'Pic003'
'004'
>> for ii = find(strncmp(x, 'Pic', 3))'
x{ii}(1:3) = [];
end
>> x
x =
'001'
'002'
'003'
'004'
strings = {'Pic001'; 'Pic002'; 'Pic003'; '004'};
numbers = regexp(strings, '(PIC)?(\d*)','match');
for cc = 1:length(numbers);
fprintf('%s\n', char(numbers{cc}));
end;