pltFor

pltFor (reads "plot for") is a Fortran-Python interface library to plot figures directly in Fortran. Here an example:

program plot_cosx

  use, intrinsic :: iso_fortran_env
  use pltFor ! load pltFor module
  implicit none
  integer(int32) :: i
  real(real64), dimension(20) :: x = (/(i, i=1, 20, 1)/)
  
  call plt_plot(x, cos(x), 'Title', 'xlabel', 'ylabel', 'plot.jpg')

end program plot_cosx

• Advantages:

  • Easy to use, easy to install.
  • Open source and modifiable.
  • Do not require to write output files to be read by external languages.
  • Do not generate external files, aside the wanted figures.
  • Performed during the Fortran execution.
  • Do not run command lines during the Fortran execution.
  • The same approach can be used to run Python script modifying the Fortran variables (the memory is shared between Fortran and Python).

• Drawbacks:

  • Do not save the variables. Therefore, to re-plot the figures, we need to run again the Fortran code.
  • Exotic plot options, such as advanced multiplot or adding annotations, are not taken into account.

How it work? The plot functions are written within a Python3 Matplotlib script. With the Python package CFFI, our script is used to generate a shared library with a C-style binding interface. Finally, the library is linked to the Fortran code with a classical C-Fortran interface.

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User guide

A more complete user guide will be available soon.

Available subroutines

Quick plot

x and y must be 1D array in double precision (you can force the conversion with real(x,8)).

call plt_plot(x, y, 'Title', 'xlabel', 'ylabel', 'plot.jpg')

Advanced plot

x and y must be 1D array in double precision (you can force the conversion with real(x,8)).

call plt_plot_adv(x, & ! Argument x (1D array float64)
                  y, & ! Argument y (1D array float64)
                  'steelblue', & ! color. Ex: b g r c m y k w grey, brown, ivory, teal, royalblue, orchid
                  'P', & ! marker. Ex: None . , o v ^ < > 1 2 3 4 8 s p P * h H + x X D d | _ 
                  'dashdot', & ! linestyle. Ex: solid dotted dashed dashdot
                  3.d0, & ! linewidth (float64)
                  12.d0, & ! markersize (float64)
                  'Title', & ! title. Leave '' for none
                  'xlabel', & ! xlabel. Leave '' for none
                  'ylabel', & ! ylabel. Leave '' for none
                  'plot.jpg') ! filename to save. MUST end with a valid format (.png, .pdf, ...)

Advanced multiplot

x and y must be 2D array in double precision organized as x(n, m) with n the number of point for a given plot and m the plot index. x and y must be the same size.

! Example for 3 plots
call plt_multiplot(mat_X(:,0:3), & ! Argument x (2D array float64 organized as (data, plot)). All the plots must have the same size
                   mat_Y(:,0:3), & ! Argument y (2D array float64 organized as (data, plot)). All the plots must have the same size
                   'steelblue; coral; lime', & ! color. Use ; as separator. Ex: b g r c m y k w grey, brown, ivory, teal, royalblue, orchid
                   '^; ,; d', & ! marker. Use ; as separator. Ex: None . , o v ^ < > 1 2 3 4 8 s p P * h H + x X D d | _ 
                   'dashdot; solid; dashed', & ! linestyle. Use ; as separator. Ex: solid dotted dashed dashdot
                   (/ 3.d0, 1.d0, 2.d0 /), & ! linewidth (float64)
                   (/ 12.d0, 15.d0, 5.d0 /), & ! markersize (float64)
                   'Title: plt_multiplot', & ! title. Leave '' for none
                   'xlabel', & ! xlabel. Leave '' for none
                   'ylabel', & ! ylabel. Leave '' for none
                   'Figs/plt_multiplot.jpg') ! filename to save. MUST end with a valid format (.png, .pdf, ...)

Scatter

x, y, s and c must be 1D array in double precision (you can force the conversion with real(x,8)).

call plt_scatter_full(x, & ! Argument x (1D array float64)
                      y, & ! Argument y (1D array float64)
                      s, & ! Argument surface area (1D array float64)
                      c, & ! Argument color (1D array float64)
                      1.d0, & ! alpha (float64) between 0 (transparent) and 1 (opaque).
                      'hsv', & ! cmap. Ex: viridis, plasma, inferno, magma, cividis, PuRd, YlGn, spring, hot, tab20c, ...
                      'H', & ! marker. Ex: None . , o v ^ < > 1 2 3 4 8 s p P * h H + x X D d | _ 
                      'Title', & ! title. Leave '' for none
                      'xlabel', & ! xlabel. Leave '' for none
                      'ylabel', & ! ylabel. Leave '' for none
                      'cmaplabel', & ! cmaplabel. Leave '' for none
                      'plot.jpg') ! filename to save. MUST end with a valid format (.png, .pdf, ...)

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Installation

Go to the folder lib and run the INSTALL file or execute

python3 pltFor_builder.py

This will create a shared library called libpltFor-0.2.so (or .dylib for MacOS). (Tips: you can move this file).

Then, add the pltFor.f90 module to your code folder. The module must be refered in your fortran code as

use pltFor

Finally, when compiling the module, you must add the path of libpltFor-0.2.so (generated above) and the path of libpython3.7m.so (for python3.7). This last library should be in the main python directory. (Tips: The path can appear during the execution of pltFor_builder.py).

gfortran path/libpltFor-0.2.so path/libpython3.7m.so -c pltFor.f90 -o pltFor.o

Installation example

An example is provided with the example.f90 program. To compile it, you can use the makefile file. Modify the Python path PATH_LIBPYTHON that include libpython3.7m.so. Then execute it and run the code

make
./a.out

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Installation errors

• If the message error while loading shared libraries occurs, you must find the path to this library and execute:

  LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/path
  export LD_LIBRARY_PATH

• For MacOS user, if the message dyld: Library not loaded: * Reason: image not found occurs, you must find the path to this library and execute:

  DYLD_LIBRARY_PATH=$DYLD_LIBRARY_PATH:/path
  export DYLD_LIBRARY_PATH

• If the message distutils.errors.LinkError: command 'x86_64-apple-darwin13.4.0-clang' failed with exit status 254 occurs, execute:

  export CC=/usr/bin/clang
  export CXX=/usr/bin/clang++

• For MacOS users, if the message library not found for -lSystemoccurs, execute

  sudo xcode-select --install

  then add -L/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/lib -lSystem to the compilation statement

• Anaconda user of MacOS Big Sur, please update Anaconda

  conda update --all   

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Notes

pltFor is still in developpment. It is planned to improve the installation and to dedicate its proper folder in usr/lib.

The library builder is inspired from a Noah Brenowitz's post

Contributing

Pull requests on the git project are welcome. For major changes, please open an issue first to discuss what you would like to change.

License

MIT