How to read this code? - Printable Version

How to read this code? - Printable Version

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How to read this code? - Jlyk - Aug-18-2021

Hello everybody. I'm new here and new one in Python. I have such piece of code and I don't know how to understand some parts of it.
Could you please help me?

from openpyxl import load_workbook, Workbook


def reader(file_name, search_string1, search_string2):                              #this is our file read function with 2 search words
    book = load_workbook(file_name, read_only=True)                                 #this is how we open it
    items = [                               # Here I need help I don't know what is going on here. We have some list(items = [])
        (o.value, )                         # What is this? 
        for i in book.active.iter_rows()                            #Here we are going over sheet
        for o in i                                                  #Here we are goking over lines
        if o.value and isinstance(o.value, str)                     #Here we compare our words with cell data
        and search_string1.lower() in o.value.lower() and search_string2.lower() in o.value.lower() #Could anybody describe this block of code in more detail
    ]                                                                                               #Or write this piece of code for newbie language
    return items


def writer(items):
    book = Workbook()
    sheet = book.active

    for row in items:
        sheet.append(row)

    book.save('result.xlsx')


if __name__ == '__main__':
    items = reader("WEG.xlsx", '5g10', 'xpj')
    writer(items)

RE: How to read this code? - Yoriz - Aug-18-2021

It is a List Comprehension

    items = [  # Here I need help I don't know what is going on here. We have some list(items = [])
        (o.value,)  # What is this?
        for i in book.active.iter_rows()  # Here we are going over sheet
        for o in i  # Here we are goking over lines
        if o.value
        and isinstance(o.value, str)  # Here we compare our words with cell data
        and search_string1.lower() in o.value.lower()
        and search_string2.lower()
        in o.value.lower()  # Could anybody describe this block of code in more detail
    ]  # Or write this piece of code for newbie language

This is the equivalent as normal for loops

    items = []
    for i in book.active.iter_rows():
        for o in i:
            if (
                o.value
                and isinstance(o.value, str)
                and search_string1.lower() in o.value.lower()
                and search_string2.lower() in o.value.lower()
            ):
                items.append((o.value,))

Edit: Included the tuple that I missed that @deanhystad reiterates below

RE: How to read this code? - deanhystad - Aug-18-2021

For some reason the code builds a list of tuples. The expanded code would be:

items = []
for i in book.active.iter_rows():
    for o in i:
        if (
            o.value
            and isinstance(o.value, str)
            and search_string1.lower() in o.value.lower()
            and search_string2.lower() in o.value.lower()
        ):
            items.append((o.value,))

And to answer the other question, (o.value,) makes a tuple that contains o.value.

a = 5
b = (a,)
c = tuple([a])
d = (a)
print(a, b, c, d)

Output:
5 (5,) (5,) 5

Notice that the trailing comma is required. In "b = (a,)" the parenthesis tell Python to make a Tuple. Without the comma, "d = (a)", the parenthesis are interpreted as a grouping operator. Do everything inside the parenthesis first as in x = (1 + 2) * 3 tells Python to add 1 and 2 before multiplying by 3.

RE: How to read this code? - Jlyk - Aug-19-2021

Thanks a lot guys! Appreciate your quick answers!