要讀取cell中的值，但是，如果cell中的值是一個公式，則讀取出來的是公式。有時候我們希望讀取到公式計算出來的結果，可以使用load_workbook()中的data_only屬性。
load_workbook()中涉及到的全部屬性，其中，read_only用於打開一個大空間的xlsx文件（否則會產生MemoryError問題——內存爆了），data_only用於讀取cell中的值（如果cell中的值是公式，則會返回計算得到的值）
filename (string or a file-like object open in binary mode c.f., zipfile.ZipFile) – the path to open or a file-like object
read_only (bool) – optimised for reading, content cannot be edited
keep_vba (bool) – preseve vba content (this does NOT mean you can use it)
guess_types (bool) – guess cell content type and do not read it from the file
data_only (bool) – controls whether cells with formulae have either the formula (default) or the value stored the last time Excel read the sheet
keep_links (bool) – whether links to external workbooks should be preserved. The default is True
原文鏈接：https://blog.csdn.net/tankloverainbow/article/details/80872901