python f'string 在 pd.Series.map 函数中不起作用

Question

我有一个pd系列，

s = pd.Series([1, 2, 3, np.nan])

当我做，

s.map('this is a string {}'.format)
[out]
0    this is a string 1.0
1    this is a string 2.0
2    this is a string 3.0
3    this is a string nan   

如何使用格式化字符串获得相同的结果？

s.map(f'this is a string {?}') ?

Answer 1

使用 lambda 函数{x}：

print (s.map(lambda x: f'this is a string {x}'))
#alternative with different value
#print (s.map(lambda val: f'this is a string {val}'))
0    this is a string 1.0
1    this is a string 2.0
2    this is a string 3.0
3    this is a string nan
dtype: object