[Python beginner memo] Python character string, path operation

I'm studying python and I'll do a lot of research, but I'll always research the same thing, so I'll put it together as a memo for myself.

This is the first post. I would be grateful if you could point out anything strange.

This section summarizes python strings and path-related functions.

os.path.join

I think join () is a common function that joins arrays etc. I understand that os.path.join () is a function that joins paths.

For example

osp.join("dir1/", "dir2")
osp.join("dir1",  "dir2")

Both

dir1/dir2

Returns.

There seem to be the following two main usages.

osp.join(path1,  path2)
osp.join(path1 + path2)

It seems that the behavior changes when "/" comes at the beginning of the argument.

path1 = "path1"
path2 = "/path2"
osp.join(path1,  path2) # /returns path2
osp.join(path1 + path2) # path1/path2

By the way, one book used it properly, but the benefits are still unknown. .. ..

If you want to use a list, add an asterisk. Reference: https://www.sejuku.net/blog/64408

For the python asterisk, see below. https://qiita.com/LouiS0616/items/1bbe0a9bb93054f6c380

format

Replace the argument of format () with the location defined by {}.

print("{}Is{}It's a yen".format("beer", 1000))
# >Beer is 1000 yen

You can also specify keywords.

print("{item}Is{price}It's a yen".format(price=2000, item="sashimi"))
# >Sashimi is 2000 yen

You can also use the dict type.

price_list = {"item":"water", "price":500}
print("{item}Is{price}It's a yen".format(**price_list))
# >Water is 500 yen

% Operator

There is a description that it is not recommended so much, but since it was a description such as a book, I will leave it.

Replaces what is defined with% s,% i, etc. with the variable after%. I understand it's like sprintf.

test_template = "%s is%i yen"
print((test_template % ("ramen",1050)))
# >Ramen is 1050 yen

I will update what I have investigated again.