How to add thousand separator to numbers in pandas

Question

Assuming that I have a pandas dataframe and I want to add thousand separators to all the numbers (integer and float), what is an easy and quick way to do it?

Answer 1

When formatting a number with , you can just use '{:,}'.format:

n = 10000
print '{:,}'.format(n)
n = 1000.1
print '{:,}'.format(n)

In pandas, you can use the formatters parameter to to_html as discussed here.

num_format = lambda x: '{:,}'.format(x)
def build_formatters(df, format):
    return {
        column:format 
        for column, dtype in df.dtypes.items()
        if dtype in [ np.dtype('int64'), np.dtype('float64') ] 
    }
formatters = build_formatters(data_frame, num_format)
data_frame.to_html(formatters=formatters)

Adding the thousands separator has actually been discussed quite a bit on stackoverflow. You can read here or here.