Just FYI, the example Dave supplied was not using python code and using a
rather strange re-definition in the R language package he was using. Or
maybe not.
Anyone not interested, skip the rest.
First, R does not use indentation for almost anything. So you can break one
long line up into many lines all over the place where it is clear you are
continuing.
Second, the ggplot package (another name for module) came along before pipes
were used a lot and made a choice to overload the meaning of the plus sign
selectively between "verbs" of sorts.
The code Thomas shared says:
- Set up the beginning of a plot using the arguments provided and create a
DATA STRUCTURE. This structure is a rather complex list structure composed
internally of many kinds of named parts, some optional.
- Then call a verb of sorts, called geom_point() to update the same data
structure appropriately and store info to be used LATER when you call the
print driver that knows how to handle this data structure. In a sense, the
first command sends the dta structure to the second command which changes it
and passes it along to
- the next verb is theme_bw() which changes all kinds of elements in the
data structure and returns the update data structure.
The result is stored as the value of g2 and NOTHING HAPPENS.
If you even wrote print(g2) or implicitly printed it at the REPL level such
as by typing "g2" or not assigning it at all to a variable at the REPL
level, then the driver that handles such an object generates a graph to
whatever output device is currently set in whatever format is set such as a
JPEG image or a PDF file.
There are errors in what Thomas wrote as an example but not what is
mentioned.
The overall flow looks like:
g2 <- ggplot(ARGS) + geom_point(ARGS) + theme_bw(ARGS)
The parentheses around the RHS are NOT needed and the above is very
typically written as:
g2 <- ggplot(ARGS) +
geom_point(ARGS) +
theme_bw(ARGS)
The plus signs at the end of each line tell the REPL to keep reading.
The code shown is not working code but was an illustration. The ggplot()
function takes many potential arguments including one for the data.frame or
tibble that holds rows and columns of data. You then have to map some
aesthetics such as what X and Y are bound to directly to some column, or
perhaps to a function involving columns. That is not shown inside the aes()
inner function and what is shown is nonsense. As usual, function arguments
are separated by commas and I assume a line or more are missing. This
example does not tell us what columns I being graphed against what other
column or other necessary things. That can sometimes be told or changed
later but I see none in this example. This function call should have ended
without a comma and with a close parentheses followed by a plus sign.
The geom_point() function that follows can be empty and then would ask for a
chart overlay showing just the points. This example added the size and color
of those points.
The last verb of theme_bw() adjusts all kinds of parameters to provide a
certain look to be basically black and white for various background items.
The example chose to include parens around everything so the plus signs
could now be anywhere, including the start of future lines. I generally do
not do things this way but it is a valid way.
I do note there is a python version of the ggplot package and maybe Thomas
is writing from that point of view in python. I have never used that.
As noted, most other R constructs use PIPES not the plus sign and I wish
this package would change to conform but it is a bit late! LOL!
Avi
-----Original Message-----
From: Python-list <python-list-bounces+avi.e.gross=gmail....@python.org> On
Behalf Of 2qdxy4rzwzuui...@potatochowder.com
Sent: Thursday, January 19, 2023 1:30 PM
To: python-list@python.org
Subject: Re: Improvement to imports, what is a better way ?
On 2023-01-19 at 12:59:21 -0500,
Thomas Passin <li...@tompassin.net> wrote:
> Well, it's an art, not a science [...]
+1
> # Create a plot
> g2 = (
> ggplot(df2,
> aes('Days Since Jan 22', # Comments can clarify these params
> + geom_point(size=.1, color='blue') # size, color params optional
> + theme_bw() # Optional theme (background, grid color, ...)
> )
You've got a comma followed by a plus sign in there, so I'm not exactly sure
where the parameters to which function begin and end.
When it starts to look like this, I begin breaking out the parameters:
label = 'Days Since Jan 22'
size = geom_point(size=.1, color='blue') theme = theme_bw()
g2 = ggplot(df2, aes(label, size, theme))
> # Compose a long string:
> msg = ('A very long line .....\n'
> + 'Another long bit of text ....'
> + 'plus another ....'
> )
If all the pieces are constants, then Python will concatenate them for
you:
msg = ('A very long line .....\n'
'Another long bit of text ....'
'plus another')
You can even mix in "f" strings:
msg = ('long line\n'
f'left text {name} right text'
'more here')
But watch out for missing spaces between the pieces! :-)
> The PEP-8 rules are good, but they can't cover all cases perfectly.
Some the PEP-8 rules are debatable. Regardless, they can't cover all cases
perfectly. (IOW, we agree on the bit that's relevant to this
thread.)
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