Help to find a string and read the next lines

[snippsat]

Here it may be easier to write an regex.
Also bye using compile and finditer make it efficient for larger files.

pattern = re.compile(r"\[DOSIMETRY_TOTAL.*\]\s+(\S+)")
for match in pattern.finditer(data):
    print(20 * '-')
    print(match.group(0)) 

Output:
[DOSIMETRY_TOTAL_DOSE_B: 00]

9.30988
--------------------
[DOSIMETRY_TOTAL_DOSE_E: 00]

8.45142
--------------------
[DOSIMETRY_TOTAL_DOSE_B: 01]

9.18214
--------------------
[DOSIMETRY_TOTAL_DOSE_E: 01]

8.41000
--------------------
[DOSIMETRY_TOTAL_DOSE_B: 02]

8.87531
--------------------
[DOSIMETRY_TOTAL_DOSE_E: 02]

8.35574
.....

data that i test with is just string of the whole file.
group(1) will be values only.

Output:
9.30988
--------------------
8.45142
--------------------
9.18214
--------------------
8.41000
--------------------
8.87531
--------------------
8.35574
--------------------
9.15688
--------------------
8.40126
--------------------
8.88971
--------------------
8.48842
.....