passing an empty string as the locale tells python to try to automatically determine the user' locale ( by examining the lang environment variable)with fallback of the locale here are some examples that show the effects of different locales on an integer and floating-point numberxy ( locale setlocale(locale lc_all" " "{ : { : }format(xyc =" locale setlocale(locale lc_all"en_us utf- "en "{ : { : }format(xyen =" , , , , locale setlocale(locale lc_all"de_de utf- "de "{ : { : }format(xyde = , although is very useful for integersit is of more limited use with floatingpoint numbers because as soon as they become large they are output using exponential form for floating-point numbersthe format specification gives us control over the fill characterthe alignment within the fieldthe signwhether to use nonlocale aware comma separator to group digits (from python )the minimum field widththe number of digits after the decimal placeand whether to present the number in standard or exponential formor as percentage the format specification for floating-point numbers is the same as for integersexcept for two differences at the end after the optional minimum width--from python after the optional grouping comma--we can specify the number of digits after the decimal place by writing period followed by an integer we can also add type character at the ende for exponential form with lowercase ee for exponential form with an uppercase ef for standard floating-point formg for "generalform--this is the same as unless the number is very largein which case it is the same as --and gwhich is almost the same as gbut uses either or also available is %--this results in the number being multiplied by with the resultant number output in format with symbol appended here are few examples that show exponential and standard formsamount ( * math pi "[{ : }[{ : }]format(amount' + ]"[{ :*> }[{ :*> }]format(amount'[**** + [***** ]"[{ :*>+ }[{ :*>+ }]format(amount'[***+ + [****+ ]the first example has minimum width of characters and has digits after the decimal point the second example builds on the firstand adds fill character if we use fill character we must also have an alignment characterso we have specified align right (even though that is the default for numbers