updates

Fixed a test with latest matplotlib. Fixes #47
Added a new option to use date formatting for the axes.

.gitignore

@@ -1,41 +1,42 @@
-bin/
-lib/
-doc/
-build/
-__pycache__
-
-# Compiled Object files
-*.slo
-*.lo
-*.o
-*.obj
-
-# Precompiled Headers
-*.gch
-*.pch
-
-# Compiled Dynamic libraries
-*.so
-*.dylib
-*.dll
-
-# Fortran module files
-*.mod
-
-# Compiled Static libraries
-*.lai
-*.la
-*.a
-*.lib
-
-# Executables
-*.exe
-*.out
-*.app
-
-# Generated Test Files
-test/*.png
-test/*.py
-
-# misc
-.DS_Store
+bin/
+lib/
+doc/
+build/
+__pycache__
+
+# Compiled Object files
+*.slo
+*.lo
+*.o
+*.obj
+
+# Precompiled Headers
+*.gch
+*.pch
+
+# Compiled Dynamic libraries
+*.so
+*.dylib
+*.dll
+
+# Fortran module files
+*.mod
+
+# Compiled Static libraries
+*.lai
+*.la
+*.a
+*.lib
+
+# Executables
+*.exe
+*.out
+*.app
+
+# Generated Test Files
+test/*.png
+test/*.py
+
+# misc
+.DS_Store
+/env

src/pyplot_module.F90

@@ -71,6 +71,9 @@ module pyplot_module
         logical :: tight_layout = .false.    !! tight layout option
         logical :: usetex      = .false.     !! enable LaTeX
 
+        character(len=:),allocatable :: xaxis_date_fmt  !! date format for the x-axis. Example: `"%m/%d/%y %H:%M:%S"`
+        character(len=:),allocatable :: yaxis_date_fmt  !! date format for the y-axis. Example: `"%m/%d/%y %H:%M:%S"`
+
         character(len=:),allocatable :: real_fmt  !! real number formatting
 
     contains
@@ -162,7 +165,7 @@ end subroutine add_str
     subroutine initialize(me, grid, xlabel, ylabel, zlabel, title, legend, use_numpy, figsize, &
                           font_size, axes_labelsize, xtick_labelsize, ytick_labelsize, ztick_labelsize, &
                           legend_fontsize, mplot3d, axis_equal, polar, real_fmt, use_oo_api, axisbelow,&
-                          tight_layout, raw_strings, usetex)
+                          tight_layout, raw_strings, usetex, xaxis_date_fmt, yaxis_date_fmt)
 
     class(pyplot),         intent(inout)        :: me              !! pyplot handler
     logical,               intent(in), optional :: grid            !! activate grid drawing
@@ -189,6 +192,8 @@ subroutine initialize(me, grid, xlabel, ylabel, zlabel, title, legend, use_numpy
     logical,               intent(in), optional :: raw_strings     !! if True, all strings sent to Python are treated as
                                                                    !! raw strings (e.g., r'str'). Default is False.
     logical,               intent(in), optional :: usetex          !! if True, enable LaTeX. (default if false)
+    character(len=*),      intent(in), optional :: xaxis_date_fmt  !! if present, used to set the date format for the x-axis
+    character(len=*),      intent(in), optional :: yaxis_date_fmt  !! if present, used to set the date format for the y-axis
 
     character(len=max_int_len)  :: width_str             !! figure width dummy string
     character(len=max_int_len)  :: height_str            !! figure height dummy string
@@ -257,6 +262,16 @@ subroutine initialize(me, grid, xlabel, ylabel, zlabel, title, legend, use_numpy
     else
         me%usetex = .false.
     end if
+    if (present(xaxis_date_fmt)) then
+        me%xaxis_date_fmt = xaxis_date_fmt
+    else
+        if (allocated(me%xaxis_date_fmt)) deallocate(me%xaxis_date_fmt)
+    end if
+    if (present(yaxis_date_fmt)) then
+        me%yaxis_date_fmt = yaxis_date_fmt
+    else
+        if (allocated(me%yaxis_date_fmt)) deallocate(me%yaxis_date_fmt)
+    end if
 
     call optional_int_to_string(font_size, font_size_str, default_font_size_str)
     call optional_int_to_string(axes_labelsize, axes_labelsize_str, default_font_size_str)
@@ -1401,11 +1416,11 @@ subroutine execute(me, pyfile, istat, python)
             write(error_unit,'(A)') 'Error closing file: '//trim(file)
         else
 
-            if (present(python)) then 
+            if (present(python)) then
                 python_ = trim(python)
-            else 
+            else
                 python_ = python_exe
-            end if 
+            end if
 
             !run the file using python:
             if (index(file,' ')>0) then
@@ -1477,6 +1492,14 @@ subroutine finish_ops(me)
         end if
         call me%add_str('')
     end if
+    if (allocated(me%xaxis_date_fmt) .or. allocated(me%yaxis_date_fmt)) then
+        call me%add_str('from matplotlib.dates import DateFormatter')
+        if (allocated(me%xaxis_date_fmt)) &
+            call me%add_str('ax.xaxis.set_major_formatter(DateFormatter("'//trim(me%xaxis_date_fmt)//'"))')
+        if (allocated(me%yaxis_date_fmt)) &
+            call me%add_str('ax.yaxis.set_major_formatter(DateFormatter("'//trim(me%yaxis_date_fmt)//'"))')
+        call me%add_str('')
+    end if
     if (me%tight_layout) then
         call me%add_str('fig.tight_layout()')
         call me%add_str('')

test/date_test.f90

@@ -0,0 +1,50 @@
+!*****************************************************************************************
+!>
+!  Unit test for [[pyplot_module]]. Using the `xaxis_date_fmt` option for x-axis dates.
+
+    program date_test
+
+    use pyplot_module, only : pyplot, wp => pyplot_wp
+
+    implicit none
+
+    integer,parameter :: n = 100
+
+    real(wp), dimension(:),allocatable   :: x     !! x values
+    real(wp), dimension(:),allocatable   :: y     !! y values
+    real(wp), dimension(:),allocatable   :: sx    !! sin(x) values
+    real(wp), dimension(:),allocatable   :: cx    !! cos(x) values
+    real(wp), dimension(:),allocatable   :: tx    !! sin(x)*cos(x) values
+    type(pyplot) :: plt   !! pytplot handler
+    integer      :: i     !! counter
+    integer      :: istat !! status code
+
+    character(len=*), parameter :: testdir = "test/"
+    character(len=*), parameter :: xaxis_date_fmt = '%m/%d/%y %H:%M:%S'
+    character(len=*), parameter :: yaxis_date_fmt = '%H:%M:%S'
+
+    ! size arrays:
+    allocate(x(n))
+    allocate(sx(n))
+    allocate(cx(n))
+    allocate(tx(n))
+
+    !generate some data:
+    x    = [(real(i,wp), i=0,size(x)-1)]/5.0_wp
+    sx   = 10*sin(x)
+    cx   = cos(x)
+    tx   = sx * cx
+
+    !2d line plot:
+    call plt%initialize(grid=.true.,xlabel='Calendar date',figsize=[20,10],&
+                        title='date test',legend=.true.,axis_equal=.true.,&
+                        tight_layout=.true., &
+                        xaxis_date_fmt=xaxis_date_fmt, yaxis_date_fmt=yaxis_date_fmt)
+    call plt%add_plot(x,sx,label='$\sin (x)$',linestyle='b-o',markersize=5,linewidth=2,istat=istat)
+    call plt%add_plot(x,cx,label='$\cos (x)$',linestyle='r-o',markersize=5,linewidth=2,istat=istat)
+    call plt%add_plot(x,tx,label='$\sin (x) \cos (x)$',linestyle='g-o',markersize=2,linewidth=1,istat=istat)
+    call plt%savefig(testdir//'datetest.png', pyfile=testdir//'datetest.py',&
+                     istat=istat)
+
+    end program date_test
+!*****************************************************************************************