Re: st: Montly data - remove month from x-axis and keep year only

[Nick Cox <njcoxstata@gmail.com>]

The underlying fallacy here is that changing the display -format- is
equivalent to changing the data to a different form.

If you have numbers that are Stata monthly dates then for dates like
Jan 2001 those numbers are like

. di ym(2001,1)
492

i.e. 500 or so as Stata works with an origin of January 1960

di ym(1960,1)
0

You have in effect told Stata to display those numbers as years and so
they are just shown as such.

di %ty 492
0492

The leading zero is just Stata doing what you told it, within a
convention of four-digit years. In other words, the underlying values
like 492 remain what they were.

Consider

. di %tmCY 492
2001

That's what you are seeking, i.e. telling Stata "it's a monthly date,
but I just want to see the years".

For the graphical problem here, the special twist is showing year
labels centrally placed, for which see an explanation in excruciating
detail

SJ-7-4  gr0030  . Stata tip 55: Better axis labeling for time points/intervals
        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  N. J. Cox
        Q4/07   SJ 7(4):590--592                                 (no commands)
        tip on labeling graphs for time points and time intervals

http://www.stata-journal.com/sjpdf.html?articlenum=gr0030

For a stern homily that changing the format only the format changes, see

SJ-12-4 dm0067  . . . . . . . . .  Stata tip 113: Changing a variable's format
        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  N. J. Cox
        Q4/12   SJ 12(4):761--764                                (no commands)
        discusses what changing a variable's format does and does
        not mean

NB: -twoway- is a command, not a function.

Nick
njcoxstata@gmail.com


On 10 February 2014 11:36, Kathrin Jacobs <jacobs.1@gmx.net> wrote:

> I have a time series plot that I constructed using the "twoway" function. My question is the following: I have monthly data, but I just want the year to show up in the x-axis.
> My time variable is formatted as %tmMon_CCYY.
>
> My x-axis currently looks like this: January 2000, January 2001, ..., January 2014 with minor ticks for the months
> I would like to have it labelled as 2000 2001,...,2014 centered over the minor ticks:
>
> |,,,,,,,,,,,|,,,,,,,,,,,|,,,,,,,,,,,|
>     2000         2001        2002
>
> I have tried various options, but if I add the %ty format, I have strange values (0480   0500   0520 ...)  instead of years on the axis
> tsline consumption xlabel(,format(%ty)) tmtick(##12)
> Does anyone know how to do this?
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