Parsing with Python regex and storing in a list

Question

Good day everyone. I just have a question regarding the use of regex in python. If I have a string code that consists of several lines of formula with variable or numeric value.

For example:

code1 = '''
g = -9
h = i + j
year = 2000
month = 0xA
date = 0b1101
sec = 1.8E3
d_1 = year + month
d_2 = date * sec
err = 0o0.1
'''

How would I be able to parse this so that I would get a list of set of strings?

lst = [{Variable}, {numeric value}, {operand}, {None of the above}]

so it would be:

lst = [{g, h, i , j, year, month, date, sec, d_1, d_2, err},{-9,2000,0xA,0b1101,1.8E3},{=, +, *},{0o0.1}]

What I did was just used split() to just separate each string and check if they are an int, or str, or non of the above and it works fine. But I want to know how to do this in regex

The LHS and RHS values seem to be divided into two sublists somewhat artibtrarily. What is the logic behind your expected output? — Tim Biegeleisen
– Tim Biegeleisen, Commented Dec 14, 2020 at 4:45

Mace · Accepted Answer · 2020-12-14 06:57:50Z

Your desired output seems not very logical. But your question is about the parsing. You can indeed use split for this in a several steps. This code parses and creates a dictionary list. I guess you can use it to create your own wanted result.

code1 = '''
g = -9
h = i + j
year = 2000
month = 0xA
date = 0b1101
sec = 1.8E3
d_1 = year + month
d_2 = date * sec
err = 0o0.1
'''

lines = code1.split('\n')

results = []

for line in lines:
    if '=' in line:
        key, right_part = line.split('=')
        print(key, right_part)
        results.append({'key': key.strip(), 'right_part': right_part.strip()})

for result in results:
    value_parts = result['right_part'].split(' ')
    if len(value_parts) == 3:
        result['values'] = [value_parts[0], value_parts[2]]
        result['operand'] = value_parts[1]
    else:
        result['values'] = value_parts[0]
        result['operand'] = None

for result in results:
    print(result)

Result

{'key': 'g', 'right_part': '-9', 'values': '-9', 'operand': None}
{'key': 'h', 'right_part': 'i + j', 'values': ['i', 'j'], 'operand': '+'}
{'key': 'year', 'right_part': '2000', 'values': '2000', 'operand': None}
{'key': 'month', 'right_part': '0xA', 'values': '0xA', 'operand': None}
{'key': 'date', 'right_part': '0b1101', 'values': '0b1101', 'operand': None}
{'key': 'sec', 'right_part': '1.8E3', 'values': '1.8E3', 'operand': None}
{'key': 'd_1', 'right_part': 'year + month', 'values': ['year', 'month'], 'operand': '+'}
{'key': 'd_2', 'right_part': 'date * sec', 'values': ['date', 'sec'], 'operand': '*'}
{'key': 'err', 'right_part': '0o0.1', 'values': '0o0.1', 'operand': None}

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