gmt subplot frames not displayed correctly

[VinceS97403]

Description of the problem

Hello, I am trying to plot two maps of Alaska using subplot 1x2. The frames produced by this command do not alternate the black and white stripes consistently. On each axis one stripe is black or white and the rest is the other color. Please let me know if this is not clear enough.

Full script that generated the error

#!/usr/bin/env bash
#gmt set  HEADER_FONT_SIZE 14p
gmt set GMT_THEME cookbook
#gmt set LABEL_OFFSET 0.2c

# Color palettes
gmt makecpt -Cmyearth_mag.cpt #-Cpolar > mag_pol.cpt #-T-500/-250/0/250/500 > mag.cpt
gmt makecpt -Cmod_jolla.cpt #coupling.cpt
gmt makecpt -Cmod_rom.cpt #/Users/vsassard/Desktop/Codes/ScientificColourMaps8/hawaii/hawaii.cpt earthquake_loc_USGS_copy.txt -D -T0/200/20 > mod_haw.cpt
gmt makecpt -Cmod_rom_slab.cpt

# Variables
gmt begin Tectonic_setting_AK
        gmt subplot begin 1x2 -Fs6i -R-165.5/-147/51/61 -JB-156/56/50/60/6i -Bxa4f30 -Bya2f30 -BWNes -Sr+t #-B+t'Tectonic Setting of the Alaska Subduction Zone'
                gmt subplot set

                # Crop the magnetic anomalies in a subregion
                gmt grdcut @earth_mag_02m_p -GMag_AK.grd -FAK_cut.txt+c
                # Plot the magnetic anomalies subset
                gmt grdimage Mag_Ak.grd -Cmyearth_mag.cpt

                # Plot the coastline and fill it in gray
                gmt coast -Df -Ggray -W #-B+s'Seismicity and Structural Variations Along-Strike'

                # Trench        
                gmt plot Trench_AK.txt -i0,1 -W1 -Sf0.3/4p+t+r -Gblack

                # Slab contours
                gmt plot alu_contours.in -Cmod_rom_slab.cpt -W1.25

                # Ruptures
                gmt plot 1946eq.xy -W2
                gmt plot 1948eq.xy -W2
                gmt plot 1964eq.xy -W2
                gmt plot simeonofslip_1m -W2
                gmt plot chignikslip_1m -W2
                gmt plot 1938slip_1m -W2
                gmt plot 1946eq.xy -W2

                # Volcanoes
                gmt plot AKvolcanoes.csv -i1,0 -h1 -St0.5 -W1 -Gred

                # Earthquakes
                gmt plot earthquake_loc_USGS_copy.txt -i2,1,3 -h10 -Sc0.2 -G+z -Cmod_rom.cpt

                # Legend 
#               gmt colorbar -Bxa40f25+l"Depth (km)" -By -Cmod_rom.cpt -DJBC
                #gmt legend


                gmt subplot set

        # Crop the magnetic anomalies in a subregion
#        gmt grdcut @earth_mag_02m_p -GMag_AK.grd -FAK_cut.txt+c
        # Plot the magnetic anomalies subset
#       gmt grdimage -R-166.5/-146/51/61 -JB-156/56/50/60/10i Mag_Ak.grd -Cmyearth_mag.cpt

                # Plot the coastline and fill it in gray
                gmt coast -Df -Ggray -W #-B+s'Seismicity and Structural Variations Along-Strike'

                # Trench        
                gmt plot Trench_AK.txt -i0,1 -W1 -Sf0.3/4p+t+r -Gblack

                # Slab contours
                gmt plot alu_contours.in -Cmod_rom_slab.cpt -W1.25

                # Locking fraction
                gmt plot gaussian_simeonof_slip_bkp -Cmod_jolla.cpt -G+z -t30 #-O -P -L -V -K #>> chig_intro.ps

                # Ruptures
                gmt plot 1946eq.xy -W2
                gmt plot 1948eq.xy -W2
                gmt plot 1964eq.xy -W2
                gmt plot simeonofslip_1m -W2
                gmt plot chignikslip_1m -W2
                gmt plot 1938slip_1m -W2

                # Volcanoes
                gmt plot AKvolcanoes.csv -i1,0 -h1 -St0.5 -W1 -Gred

                # Stations
                gmt plot AK_stations.csv -i1,0 -h1 -Sc0.25 -W1,white -Gpurple

#               gmt colorbar -Bxa40f25+l"Depth (km)" -By -Cmod_rom.cpt -DJBC
#               gmt set MAP_LABEL_OFFSET 15p
                gmt colorbar -Bx -Bya0.2f30+l"Locking fraction" -Cmod_jolla.cpt -DJMR
        gmt subplot end
        gmt colorbar -Bxa40f25+l"Depth (km)" -By -Cmod_rom.cpt -DJBC
gmt end show

Full error message

No error message

Actual outcome

Expected outcome
This is what I got when not using subplot

System information

• Operating system: macOS Ventura 13.5
• GMT version (gmt --version): 6.4

[welcome]

👋 Thanks for opening your first issue here! Please make sure you filled out the template with as much detail as possible. We appreciate that you took the time to contribute!

Please make sure you read our Contributing Guide and abide by our Code of Conduct.

[joa-quim]

Can you shrink this to an example using only basemap?
And also, use the forum to ask this type of questions (though possible, it's unlikely a GMT bug).

[VinceS97403]

Hi Joaquim, thank you for coming back to me so quickly. My apologies for posting in the wrong location and the delay I'm very new to GMT so I'm still learning all the commands, here is the new script:

#!/usr/bin/env bash
#gmt set  HEADER_FONT_SIZE 14p
gmt set GMT_THEME cookbook
#gmt set LABEL_OFFSET 0.2c

# Variables
gmt begin Tectonic_setting_AK
        gmt subplot begin 1x2 -Fs6i -R-165.5/-147/51/61 -JB-156/56/50/60/6i -Bxa4f30 -Bya2f30 -BWNes -Sr+t #-B+t'Tectonic Setting of the Alaska Subduction Zone'
                gmt subplot set
                gmt basemap -Bxa4f30 -Bya2f30 #-B+s'Seismicity and Structural Variations Along-Strike'

                gmt subplot set
                gmt basemap -Bxa4f30 -Bya2f30 #-B+s'Seismicity and Structural Variations Along-Strike'
        gmt subplot end
get end show

Here's what it produces:
![image](https://github.com/GenericMappingTools/gmt/assets/57848677/3c43dff5-6a7d-4517-b46b-942974e8f3ed)

[joa-quim]

Besides, your example is non-reproducible so I'm closing this (please resubmit in forum with a reproducible example).

[yvonnefroehlich]

I feel the appearance of the frame of the y or latitude axis is because of the relation of your -B settings to the latitude range of your study region (-R):

# Variables
gmt begin Tectonic_setting_AK
        gmt subplot begin 1x2 -Fs6i -R-165.5/-147/51/61 -JB-156/56/50/60/6i -Bxa4f30 -Bya2f30 -BWNes -Sr+t 
                gmt subplot set

-Bya2f30 gives y ticks in steps of 30. However, your study region extends only over a latitude range of 10° between 51° N and 61° N (-R-165.5/-147/51/61). For y ticks in steps of 2 you need -Bya2f2.

And as already mentioned by @joa-quim, for any follow-up questions, please use the GMT forum at https://forum.generic-mapping-tools.org/ .

[joa-quim]

Hmm, we may have a bug(ghis) behavior here but I think you made a mistake with the f30. You probably meant f30m

gmt basemap -Bxa4f30m -Bya2f30 -R-165.5/-147/51/61 -JB-156/56/50/60/6i -png lixo

[VinceS97403]

Thank you for both of your insights, it's completely my fault, I made a mistake with my usage of f, I though I was controlling another parameter instead, thank you very much for your help.