浮動小数点値を使用して Pandas DataFrame の特定の列にカスタム書式設定を適用する方法

df = pd.DataFrame([123.4567, 234.5678, 345.6789, 456.7890],
                  index=['foo','bar','baz','quux'],
                  columns=['cost'])

print(df)

         cost
foo   123.4567
bar   234.5678
baz   345.6789
quux  456.7890

import pandas as pd
pd.options.display.float_format = '${:,.2f}'.format
print(df)

        cost
foo  3.46
bar  4.57
baz  5.68
quux 6.79

df = pd.DataFrame([123.4567, 234.5678, 345.6789, 456.7890],
                  index=['foo','bar','baz','quux'],
                  columns=['cost'])

df['foo'] = df['cost']
df['cost'] = df['cost'].map('${:,.2f}'.format)

         cost       foo
foo   3.46  123.4567
bar   4.57  234.5678
baz   5.68  345.6789
quux  6.79  456.7890