Python 替换 function 中的“搜索”参数是否有限制？

Question

I am using Python to search and replace a string in a.txt file. I need to replace the value 0.000001 (6 decimal places), the code does not replace this value but will replace 0.0001 (4 decimal places). Therefore, is there some limit on this input argument (see code below)?

a0 = 0.000001
ka = 0.1
dt = 7
an = a0+ka*dt

with open('file.txt', 'r') as f:
    data1 = f.read()
    data1 = data1.replace(str(a0), str(an), 1)

with open ('file.txt', 'w', 1) as f:
    f.write(data1)

Answer 1

It is not a matter of "limit", but of numeric notation:

>>> a0 = 0.000001
>>> print(a0)
1e-06
>>> a0 = 0.0001
>>> print(a0)
0.0001
>>>

The "0.000001" string read from file won't get replaced because the replace() method will be looking for "1e-06". The same does not occur with "0.0001".

Format a0 as float , instead:

    ...
    data1 = data1.replace(str("%f" % a0), str(an), 1)
    ...