Read .arrays txt files with python?

Question

Traditionally, to read a file filled with an array in python, I use the following syntax

x, y, z = loadtxt("myfile.txt", unpack=True)

It works well for single-array files.

Now, I have a more complicated file :

1.5 3.5 2.5 1.6
4
3
1 2 3 4 5
6 7 8 9 10
11 12 13 14 15
16 17 18 19 20
1 2
3 4
5 6

What I want to do is the following thing :

1.5 3.5 2.5 1.6 -> I want to put them in an array of three variables + 1 scalar

4 -> A = 4, Number of lines of my first array

3 -> B = 3, Number of lines of my second array

My first array with A = 4 lines that I want to load in 5 variables (like the command loadtxt("", unpack = True)

1 2 3 4 5
6 7 8 9 10
11 12 13 14 15
16 17 18 19 20

My first array with B = 3 lines that I want to load in 2 variables (like the command loadtxt("", unpack = True)

1 2
3 4
5 6

Is there any technique to do this kind of things in python ?

Thank you very much.

Answer 1

You are specifying your own file format, which is not very useful. I would suggest using an existing format such as JSON:

myfile.txt:

{
    "a" : [
        [1, 2, 3, 4, 5],
        [6, 7, 8, 9, 10],
        [11, 12, 13, 14, 15],
        [16, 17, 18, 19, 20]
    ],
    "b" : [
    ...
    ]
}

read.py

import json
myfile = open("myfile.txt")
myVars = json.load(myfile)
myfile.close()
myVars['a']

Answer 2

you can open a file in python like so:

f = open("myfile.txt")

now you can go through all lines and in each line you can split it by a space:

for line in f.readlines():
    linearray = line.split(' ')
    arraylength = len(linearray)
    print("Array length: "+str(arraylength))

the rest is up to you.