[python] Converting Float to Dollars and Cents

First of all, I have tried this post (among others): Currency formatting in Python. It has no affect on my variable. My best guess is that it is because I am using Python 3 and that was code for Python 2. (Unless I overlooked something, because I am new to Python).

I want to convert a float, such as 1234.5, to a String, such as "$1,234.50". How would I go about doing this?

And just in case, here is my code which compiled, but did not affect my variable:

money = float(1234.5)
locale.setlocale(locale.LC_ALL, '')
locale.currency(money, grouping=True)

Also unsuccessful:

money = float(1234.5)
print(money) #output is 1234.5
'${:,.2f}'.format(money)
print(money) #output is 1234.5

df_buy['BUY'] = df_buy['BUY'].astype('float')
df_buy['BUY'] = ['€ {:,.2f}'.format(i) for i in list(df_buy['BUY'])]

In python 3, you can use:

import locale
locale.setlocale( locale.LC_ALL, 'English_United States.1252' )
locale.currency( 1234.50, grouping = True )

Output

'$1,234.50'

Building on @JustinBarber's example and noting @eric.frederich's comment, if you want to format negative values like -$1,000.00 rather than $-1,000.00 and don't want to use locale:

def as_currency(amount):
    if amount >= 0:
        return '${:,.2f}'.format(amount)
    else:
        return '-${:,.2f}'.format(-amount)

you said that:

`mony = float(1234.5)
print(money)      #output is 1234.5
'${:,.2f}'.format(money)
print(money)

did not work.... Have you coded exactly that way? This should work (see the little difference):

money = float(1234.5)      #next you used format without printing, nor affecting value of "money"
amountAsFormattedString = '${:,.2f}'.format(money)
print( amountAsFormattedString )

Personally, I like this much better (which, granted, is just a different way of writing the currently selected "best answer"):

money = float(1234.5)
print('$' + format(money, ',.2f'))

Or, if you REALLY don't like "adding" multiple strings to combine them, you could do this instead:

money = float(1234.5)
print('${0}'.format(format(money, ',.2f')))

I just think both of these styles are a bit easier to read. :-)

(of course, you can still incorporate an If-Else to handle negative values as Eric suggests too)