Convert blocks into arrays

Question

I have a text file containing data in form of blocks. Something like:

File description
Used units
Additional info
T[K]
50 75 100
125 150 175
200 225 250
Field_1
0.1 0.2 0.3
0.4 0.5 0.6
0.7 0.8 0.9
Field_2
1.0 2.0 3.0
4.0 5.0 6.0
7.0 8.0 9.0

I need to skip the lines without data, and read and convert the three blocks with data into three arrays. Ideally, I want to use a generator that can identify the lines with T[K], Field_1, Field_2, and separately collect whatever is in the following block of three lines.

Something that starts like this:

def npgenfromtxtgenerator(file_name):
    with open(file_name) as fp:
        for line_no, line in enumerate(fp):
            if line.startswith('Te[eV]'):
                # Make first array
            if line.startswith('Field_1'):
                # Make second array
            if line.startswith('Field_2'):
                # Make third array

Many thanks

Answer 1

Try:

s = """\
File description
Used units
Additional info
T[K]
50 75 100
125 150 175
200 225 250
Field_1
0.1 0.2 0.3
0.4 0.5 0.6
0.7 0.8 0.9
Field_2
1.0 2.0 3.0
4.0 5.0 6.0
7.0 8.0 9.0"""

import re
import numpy as np
from io import StringIO

fields = ["T[K]", "Field_1", "Field_2"]
pat = "|".join(map(re.escape, fields))
pat = re.compile(fr"^({pat})([\s\d.-]+)", flags=re.M | re.S)

out = {n: np.loadtxt(StringIO(a)) for n, a in pat.findall(s)}

# pretty print the dictionary:
for k, v in out.items():
    print(k)
    print(v)
    print("-" * 80)

Prints:

T[K]
[[ 50.  75. 100.]
 [125. 150. 175.]
 [200. 225. 250.]]
--------------------------------------------------------------------------------
Field_1
[[0.1 0.2 0.3]
 [0.4 0.5 0.6]
 [0.7 0.8 0.9]]
--------------------------------------------------------------------------------
Field_2
[[1. 2. 3.]
 [4. 5. 6.]
 [7. 8. 9.]]
--------------------------------------------------------------------------------