Regex python: match multi-line float values between brackets

Match grouped multi-line float values between brackets

In the below example data, I want to extract all the float values between brackets belonging only to "group1" using regex, but not the values from other groups ("group2", "group3" etc.). A requirement is that it is done via regex in python. Is this possible with regex at all?

Regex patterns attempts:

I tried the following patterns, but they capture either everything or nothing:

1. Matches every float value in all groups: ([+-]*\d+\.\d+),
2. Matches no value in any groups: group1 = \[ ([+-]*\d+\.\d+), \]

What should I do to make this work? Any suggestions would be very welcome!

Example data:

group1 = [
 1.0,
 -2.0,
 3.5,
 -0.3,
 1.7,
 4.2,
]


group2 = [
 2.0,
 1.5,
 1.8,
 -1.8,
 0.7,
 -0.3,
]


group1 = [
  0.0,
  -0.5,
  1.3,
  0.8,
  -0.4,
  0.1,
]