How do I add commas to numbers using fprintf?
显示 更早的评论
Hello,
How do I add commas to numbers using fprintf? My customer wants me to write out tables and have commas in the numbers to better read it. For instance, 123456789.0 would be written out as 123,456,789.0. Thanks.
Best regards,
Bill Rooker
采纳的回答
fprintf cannot do that, but you will find several FEX submissions that can create a string with commas as thousands separators:
If you read the comments to those submissions you will also find several improvements to consider.
Another easy one-line approach:
str = ["1234567890.123456789";"-1234567890";"0"]
str = regexprep(str,'(?<!\.\d*)\d{1,3}(?=(\d{3})+\>)','$&,')
4 个评论
Bill Rooker
2017-3-9
移动：Dyuman Joshi
2023-9-15
Dyuman Joshi
2023-9-15
@Stephen23, could you recommend some good resources for learning the use of regexp() and regexprep() in MATLAB?
The only resources I really use are the MATLAB documentation:
etc.
You can find some online tutorials etc that explain regular expression concepts** but these often are based on Perl or JavaScript or Python or whatever regular expressions (i.e. not the same details) so once you really need to know the details then the only place to look is the MATLAB documentation. Be prepared to read those pages many times.
If you want to experiment then you might find this useful:
** as well as many websites offering all kinds of automagic things with regular expressions.
Dyuman Joshi
2023-9-16
I tried working with the documentation pages of regexp() and regexprep(), but haven't been successful with it, as they are not clear/specific enough to me and do not provide sufficient examples to understand the functionality properly.
Thank you very much for the links, I didn't know about these pages, they are what I was looking for!
I have also tried a few online tutorials, but as you mentioned, the functionality of regexp() in other languages are different than in MATLAB.
I will also look into the FEX submission you have link, it does look very extensive, but for now, I will start from the basics with the documentation pages you linked.
Once again, Thank you!
更多回答（4 个）
Ted Shultz
2018-6-13
function numOut = addComma(numIn)
jf=java.text.DecimalFormat; % comma for thousands, three decimal places
numOut= char(jf.format(numIn)); % omit "char" if you want a string out
end
Hope that helps! --ted
5 个评论
Roscoe Cook
2019-5-15
Worked great for me! Perhaps this should be the accepted answer. Thanks!
Stargaet
2019-7-19
very good! thanks!
Kouichi C. Nakamura
2020-2-15
Thanks! Extended it to 2d matrix.
function B = AddCommaArr(A)
B = strings(size(A));
for i = 1:size(A,1)
for j = 1:size(A,2)
B(i,j) = addComma(A(i,j));
end
end
function numOut = addComma(numIn)
jf=java.text.DecimalFormat; % comma for thousands, three decimal places
numOut= char(jf.format(numIn)); % omit "char" if you want a string out
end
end
Daven Gooden
2020-11-10
@Ted Shultz: Spot on! Very clean and easy to understand/use! Thank you very mutch!
Edwin Cortez
2022-2-2
编辑：Edwin Cortez
2022-2-2
Great ! Thanks
Jim Svensson
2021-2-15
9 个投票
I feel that in 2021 this functionality should be supported by sprintf/fprintf.
3 个评论
Jim Svensson
2023-9-15
移动：Dyuman Joshi
2023-9-15
I feel that in 2023 this functionality should be supported by sprintf/fprintf.
Dyuman Joshi
2023-9-15
@Jim Svensson If you want to have a functionality implemented in MATLAB, you can raise a feature request for it.
I believe you will need a strong justification to convince TMW as to why they should implement it.
Image Analyst
2023-9-16
It would certainly be a convenience if they had a letter to do that conversion, like p or whatever (some unused letter), like
x = 12345678.912345
fprintf('Number = %p.\n', x);
'12,345,678.912'
See my attached utility function that inserts commas to make a string out of a number. Then in your fprintf you print the string with %s instead of %d or %f. For example:
number = 1234567;
fprintf('The number is %s.\n', CommaFormat(number));
Using pattern
vec = 123456789;
txt = string(vec);
pat1 = lookBehindBoundary(digitsPattern); % (?<=\d)
pat2 = asManyOfPattern(digitsPattern(3),1); % (\d{3})+
pat3 = lookAheadBoundary(pat2+lineBoundary("end")); % (?=(\d{3})+$)
pat4 = pat1+pat3; % (?<=\d)(?=(\d{3})+$)
replace(txt,pat4,",")
1 个评论
vec = 1234.56789
txt = string(vec);
pat1 = lookBehindBoundary(digitsPattern); % (?<=\d)
pat2 = asManyOfPattern(digitsPattern(3),1); % (\d{3})+
pat3 = lookAheadBoundary(pat2+lineBoundary("end")); % (?=(\d{3})+$)
pat4 = pat1+pat3; % (?<=\d)(?=(\d{3})+$)
replace(txt,pat4,",")
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