# Plot -w\*flag\* bug?

**URL:** <https://forum.generic-mapping-tools.org/t/plot-w-flag-bug/2556>\
**Category:** Q&A\
**Created:** [January 27, 2022, 5:31pm UTC](https://forum.generic-mapping-tools.org/t/plot-w-flag-bug/2556 "2022-01-27T17:31:25Z")\
**Posts on this page:** 7\
**Page:** 1

<div class="post-metadata">

**Author:** ![PlanetGus](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/planetgus/32/303_2.png) [@PlanetGus](https://forum.generic-mapping-tools.org/u/PlanetGus)\
**Post date:** [January 27, 2022, 5:31pm UTC](https://forum.generic-mapping-tools.org/t/plot-w-flag-bug/2556/1 "2022-01-27T17:31:25Z")

</div>

Hi there,

I have a time-series I’d like to plot.  
I start by generating the points (with `gmt math`, see below) between 1 (January 1st) and 365 (December 31st).

1. Can someone check where I have this “extra operand” left on the stack ?
2. For some reason if I specify x to be “time” via `-JX10ct/10c`, I got date format HH:MM instead of days despite :
  - specifying `--TIME_UNIT=d`
  - specifying `--DATE_FORMAT_OUT=o` (for abbreviated month)

3. Is it possible to shift the x-frame to 0 (middle of the plot) ?

Thanks !

```auto
gmt math -T1/365/1 2 PI MUL T 1 SUB MUL 365 DIV STO@r \
0.006818 \
@r COS 0.39912 MUL SUB \
@r SIN 0.0757 MUL ADD \
2 @r MUL COS 0.006758 MUL SUB \
2 @r MUL SIN 0.000907 MUL ADD \
3 @r MUL COS 0.002697 MUL SUB \
3 @r MUL SIN 0.00148 MUL ADD \
180 PI DIV MUL = data.txt

```

```auto
gmt begin test png
    gmt plot data.txt -R-4/9/-25/25 -JX10ct/10c --TIME_UNIT=d -wa
    gmt basemap -Bxaf -Byaf+u@. -BWS+t"Curve" --MAP_FRAME_TYPE=graph --MAP_VECTOR_SHAPE=0.5 --FORMAT_DATE_OUT=o
gmt end show

```

---

<div class="post-metadata">

**Author:** ![PlanetGus](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/planetgus/32/303_2.png) [@PlanetGus](https://forum.generic-mapping-tools.org/u/PlanetGus)\
**Post date:** [January 27, 2022, 10:35pm UTC](https://forum.generic-mapping-tools.org/t/plot-w-flag-bug/2556/2 "2022-01-27T22:35:31Z")

</div>

Obviously I could simply create a vector `-T-101/264/1` and avoid `-w` … but where’s the fun in that ?

```auto
gmt math -T-99/266/1 2 PI MUL T 1 SUB MUL 365 DIV STO@r \
0.006818 \
@r COS 0.39912 MUL SUB \
@r SIN 0.0757 MUL ADD \
2 @r MUL COS 0.006758 MUL SUB \
2 @r MUL SIN 0.000907 MUL ADD \
3 @r MUL COS 0.002697 MUL SUB \
3 @r MUL SIN 0.00148 MUL ADD \
180 PI DIV MUL = data.txt

gmt begin test png
    gmt plot data.txt -R-99/266/-25/25 -JX10ct/10c -BW+t"Curve" -Byaf+u@. --MAP_FRAME_TYPE=graph --TIME_UNIT=d 
    gmt basemap -BS -Bxa1Of1O --FORMAT_DATE_MAP=o --FORMAT_TIME_PRIMARY_MAP=a --MAP_FRAME_TYPE=graph --TIME_UNIT=d -Y5c
gmt end show

```

 ![test](https://canada1.discourse-cdn.com/flex047/uploads/gmt/original/2X/3/3f0b73aab78893a37309bab7db701f3c7aa3f40d.png)

Still … if that could be achieved easily with -w_flag_ I’m interested …

---

<div class="post-metadata">

**Author:** ![pwessel](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/pwessel/32/30_2.png) [@pwessel](https://forum.generic-mapping-tools.org/u/pwessel)\
**Post date:** [January 28, 2022, 2:51am UTC](https://forum.generic-mapping-tools.org/t/plot-w-flag-bug/2556/3 "2022-01-28T02:51:51Z")

</div>

I think `STO@r` does not pop anything off the stack, it just saves that shorthand, so you still have what you call @r sitting on the stack. If you add POP after STO@r it fixes it.

I think **-wa** (as well as the other time wrappers) expect absolute time but you are giving relative time.

Very nice though!

---

<div class="post-metadata">

**Author:** ![pwessel](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/pwessel/32/30_2.png) [@pwessel](https://forum.generic-mapping-tools.org/u/pwessel)\
**Post date:** [January 28, 2022, 2:53am UTC](https://forum.generic-mapping-tools.org/t/plot-w-flag-bug/2556/4 "2022-01-28T02:53:28Z")

</div>

Also I checked the gmt math documentation and it does mention this:

Note that **STO** and **CLR** leave the stack unchanged

---

<div class="post-metadata">

**Author:** ![PlanetGus](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/planetgus/32/303_2.png) [@PlanetGus](https://forum.generic-mapping-tools.org/u/PlanetGus)\
**Post date:** [January 31, 2022, 2:24pm UTC](https://forum.generic-mapping-tools.org/t/plot-w-flag-bug/2556/5 "2022-01-31T14:24:34Z")

</div>

> [@pwessel](#):
>
> I think **-wa** (as well as the other time wrappers) expect absolute time but you are giving relative time.

I haven’t tried, but do you think using `-ft` in `plot` would help ? Or do I simply use absolute time in `math`?

---

<div class="post-metadata">

**Author:** ![PlanetGus](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/planetgus/32/303_2.png) [@PlanetGus](https://forum.generic-mapping-tools.org/u/PlanetGus)\
**Post date:** [February 1, 2022, 1:13am UTC](https://forum.generic-mapping-tools.org/t/plot-w-flag-bug/2556/6 "2022-02-01T01:13:49Z")

</div>

@pwessel  
One last bit … sorry it’s for my sanity … Is there an easy way to get rid of the first folded “September” ?  
I tried to play with -Ba1O+_phase_ but it was not conclusive…

```auto
#!/bin/bash
# basemap, begin, coast, grdimage, grdmath, info, inset, legend, makecpt, math, plot, text

gmt math -foT --TIME_UNIT=d -T0/365/1 2 PI MUL T 1 SUB MUL 365 DIV STO@r POP \
                                0.006818 \
                                @r COS 0.39912 MUL SUB \
                                @r SIN 0.0757 MUL ADD \
                                2 @r MUL COS 0.006758 MUL SUB \
                                2 @r MUL SIN 0.000907 MUL ADD \
                                3 @r MUL COS 0.002697 MUL SUB \
                                3 @r MUL SIN 0.00148 MUL ADD \
                                180 PI DIV MUL = declination.txt

active_day="2012-12-21T"
active_day_rel=$(gmt math -Q $active_day $(gmt math -Q -fT $active_day --FORMAT_DATE_OUT=yyyy --TIME_UNIT=y --FORMAT_CLOCK_OUT=- =)-01-01T SUB --TIME_UNIT=d =)
active_line=$(gmt math -Q $active_day_rel 1 ADD =)

wrap_ref="1970-09-23T"
wrap_shift=$(gmt math -Q $wrap_ref 1970-12-31T SUB --TIME_UNIT=d 365 DIV =)
wrap_close=$(gmt math -Q $wrap_shift 1 ADD =)

wrap_day=$(gmt math -Q $active_day_rel 365 DIV STO@r $wrap_close GT 1 MUL STO@r2 POP @r @r2 SUB =)

delta=$(echo $(awk -v var=$active_line 'NR==var {print $2}' declination.txt))
delta_max=$(gmt info declination.txt -C -o3)

gmt begin test png

    gmt plot declination.txt -R$wrap_shift/$wrap_close/-25/25 -wy -JX10c -BW -Byaf+u@. --MAP_FRAME_TYPE=graph
    echo $wrap_day $delta | gmt plot -Sc0.1c -Gred -Wfaint,black
    gmt basemap -R$wrap_ref/$(gmt math -Q -fT $wrap_ref 365 ADD --TIME_UNIT=d =)/-25/25 -BS -Bxa1Of --FORMAT_DATE_MAP=o --FORMAT_TIME_PRIMARY_MAP=a --MAP_FRAME_TYPE=graph -Y5c 
    gmt text -Dj0.2c -N -F+f+j -Y-5c <<- EOF
		1971-06-21T 0 12p,Times-Roman BC Boreal summer
		1970-12-31T 0 12p,Times-Roman BC Austral summer
		$wrap_ref 30 12p,Symbol RT d
	EOF

    gmt inset begin -DjBR+w3.5c+o-3c/0.25c
        
        gmt grdmath -Rg -I0.5 X SIND = illu.nc
        gmt makecpt -Cgray -T-1/0 -I > illu.cpt
		
        gmt coast -Rg -JG0/0/3c+w$(gmt math -Q $delta_max -1 MUL =) -Dc -Ggray -A5000 -Bg -Wfaint -X0.25 -Y0.25
        gmt grdimage -JG0/0/3c+w$(gmt math -Q $delta $delta_max ADD -1 MUL =) illu.nc -C -t25
        gmt plot -JG0/0/3.5c+w$(gmt math -Q $delta_max -1 MUL =) -Wthin,black -Am -X-0.25 -Y-0.25 <<- EOF
			0 -89
			0 89
		EOF
        gmt plot -Sv0.15c+ea+h0+a60+gred -Wthicker,red -N <<- EOF
			-90 $delta $(gmt math -Q $delta $delta_max ADD -1 MUL =) 0.3c 
		EOF

    gmt inset end

    gmt legend -DjTR+o-3c/-1c -F <<- EOF
		H 14p,Helvetica-Bold Solar declination
		D 5p 1p
		S 0.5c c 0.1c red faint 1c Observed day
		S 0.5c v0.15c+h0+ea+a60 0.3c red thicker,red 1c Solar equatorial plan
	EOF
gmt end show

```

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<div class="post-metadata">

**Author:** ![PlanetGus](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/planetgus/32/303_2.png) [@PlanetGus](https://forum.generic-mapping-tools.org/u/PlanetGus)\
**Post date:** [February 2, 2022, 10:59am UTC](https://forum.generic-mapping-tools.org/t/plot-w-flag-bug/2556/7 "2022-02-02T10:59:42Z")

</div>

I tried to add `-Bx+el` but it has no effect whatsoever …

(FYI : the option `+el` works on minimal test)  
…

Ok it’s just not compatible with dates apparently