Question

I would like to turn a number into a string using a comma as a thousands separator. Something like:

x = 120501231.21;
str = sprintf('%0.0f', x);

but with the effect

str = '120,501,231.21' 

If the built-in fprintf/sprintf can’t do it, I imagine cool solution could be made using regular expressions, perhaps by calling Java (which I assume has some locale-based formatter), or with a basic string-insertion operation. However, I’m not an expert in either Matlab regexp’s or calling Java from Matlab.

Related question: How can I print a float with thousands separators in Python?

Is there any established way to do this in Matlab?

Answer 1

One way to format numbers with thousands separators is to call the Java locale-aware formatter. The “formatting numbers” article at the “Undocumented Matlab” blog explains how to do this:

>> nf = java.text.DecimalFormat;
>> str = char(nf.format(1234567.890123))

str =

1,234,567.89     

where the char(…) converts the Java string to a Matlab string.

voilà!