Everyone's right here, in a sense.
-line- can be a separate command. It is, in that circumstance,
an abbreviation for -twoway line-, which is in turn
an abbreviation for -graph twoway line-.
. viewsource line.ado
shows the innards.
In essence, wired-in graph commands are all calls
to -graph-, or wrappers for calls (to calls ( ... ))
to -graph-.
But StataCorp were well aware that users probably don't want
to type
. graph twoway line ...
whenever they want a line plot, hence the convenient
abbreviations.
(FWIW, I always use the || notation. There are plenty
enough parentheses already in a typical -graph- command.)
Nick
n.j.cox@durham.ac.uk
"Svend Juul" <SJ@SOCI.AU.DK>
In a response to Scott C., Scott M. wrote, among other things:
2. It doesn't appear that the -legend(order())- (or the ytitle,
yscale....)
are attached to one of the -line- commands.
- and suggested:
twoway line mpg price if fore == 0 ,sort lc(blue) lp(dash) ///
|| line mpg price if fore == 1 , sort lc(black) ///
legend(order(1 "white sex ratio" 2 "black sex ratio"))
---------------------------------------------------------------
Stata graph commands can be complex; I think it is helpful to keep the
terminology straight:
-line- is not a command; it is a plot specification as part of a
-twoway- graph command.
...
Personal view: I think the || notation is a lot less transparent than
the () notation. So I would write the above command:
twoway ///
(line mpg price if fore == 0 , sort lc(blue) lp(dash)) ///
(line mpg price if fore == 1 , sort lc(black)) ///
, ///
legend(order(1 "white sex ratio" 2 "black sex ratio"))
Here we have a graph command (twoway) with two plot specifications
(line); each plot specification has options (sort, etc.). The graph
command also has an option: (legend()). ytitle() and yscale() would be
graph options, too. I gave the comma separating the graph command body
from the graph options a line of its own, just for visual clarity.
Stata often can be quite tolerant to deviations from the strict rules,
as Scott M.'s example shows (it actually works), but I think that things
are easier to understand when sticking to the rules.
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