Modify monthly scale on x axis

[Alessandro Sovera]

I need to modify the x-axis of this line plot so that the first value on the axis is 1928m1 and the last one is 1933m12, with a proper amount of intermediate values.

I tried using the Graph Editor menu from the Graph window but I cannot insert letters in the boxes (e.g. values as 1928m1). Then I tried to use the values I got immediately after the ym function, which are, respectively for 1928m1 and 1933m12, -384 and -313. But now the problem is that I do not know which Delta value to insert because I can't compute the distance in time using this format.

Does anybody have a suggestion? Ty

[Nick Cox]

There are several ways to do this. Here's one I like. Using display as a calculator shows that the limits you want are -384 and -313. So use those values in an xsc(r()) option.

That's not the quickest or slickest way to do it, but it connects with what Stata sees at data level.

. di ym(1928, 1)
-384

. di ym(1933, 12)
-313

[Alessandro Sovera]

Thanks Nick.

So the idea would be to run something like graph

 twoway line typhus date, xsc(range(-384, -313)

?

In any case, how could I add other intermediate values on the axis?

[Nick Cox]

You'd need an extra parenthesis. I wouldn't plot the graph as in #1. I would put years (only) in the middle of each year and ticks only at the end of each year.

Here's some technique:

clear 
set obs 72 
gen mdate = ym(1927, 12) + _n 
set seed 2803
set scheme s1color
gen whatever = runiform()

line whatever mdate, xla(`=ym(1928, 6) + 0.5'(12)`=ym(1933, 6) + 0.5', format(%tmCY) noticks) ///
xtic(`=ym(1927, 12)+0.5'(12)`=ym(1933, 12)+0.5', tlength(*3)) xtitle("")

[Alessandro Sovera]

Thank you for your kind suggestion. Then to move the ticks, I would have to modify the option xtic, right?

[Nick Cox]

Indeed. If you want them in a different place, you need to say where that is. I am interested to know where would be a better place.