A Fortran library providing a convenient interface for plotting with Gnuplot.
This library is tailored to write script files for GNUPLOT. As such, GNUPLOT is required to make use of the output of this library. GNUPLOT can be found here.
Documentation can be found here
CMakeThis library can be built using CMake. For instructions see Running CMake.
FPM can also be used to build this library using the provided fpm.toml.
fpm buildThe FPLOT library can be used within your FPM project by adding the following to your fpm.toml file.
[dependencies]
fplot = { git = "https://github.com/jchristopherson/fplot" }The FPLOT library depends upon the following libraries.
This example illustrates how to plot two-dimensional data.
program example
use, intrinsic :: iso_fortran_env
use fplot_core
implicit none
! Parameters
integer(int32), parameter :: n = 1000
! Local Variables
real(real64), dimension(n) :: x, y1, y2
type(plot_2d) :: plt
type(plot_data_2d) :: d1, d2
class(plot_axis), pointer :: xAxis, yAxis
type(legend), pointer :: leg
! Initialize the plot object
call plt%initialize()
! Define titles
call plt%set_title("Example Plot")
call plt%set_font_size(14)
xAxis => plt%get_x_axis()
call xAxis%set_title("X Axis")
yAxis => plt%get_y_axis()
call yAxis%set_title("Y Axis")
! Establish legend properties
leg => plt%get_legend()
call leg%set_is_visible(.true.)
call leg%set_draw_inside_axes(.false.)
call leg%set_horizontal_position(LEGEND_CENTER)
call leg%set_vertical_position(LEGEND_BOTTOM)
call leg%set_draw_border(.false.)
! Define the data, and then add it to the plot
x = linspace(0.0d0, 10.0d0, n)
y1 = sin(5.0d0 * x)
y2 = 2.0d0 * cos(2.0d0 * x)
call d1%define_data(x, y1)
call d2%define_data(x, y2)
! Define properties for each data set
call d1%set_name("Data Set 1")
call d1%set_draw_markers(.true.)
call d1%set_marker_frequency(10)
call d1%set_marker_style(MARKER_EMPTY_CIRCLE)
call d1%set_marker_scaling(2.0)
call d2%set_name("Data Set 2")
call d2%set_line_style(LINE_DASHED)
call d2%set_line_width(2.0)
! Add the data sets to the plot
call plt%push(d1)
call plt%push(d2)
! Let GNUPLOT draw the plot
call plt%draw()
end programThis is the plot resulting from the above program.
Another example of a similar two-dimensional plot to the plot in example 1 is given below. This plot shifts the x-axis to the zero point along the y-axis.
! fplot_2d_2.f90
program example
use, intrinsic :: iso_fortran_env
use fplot_core
implicit none
! Parameters
integer(int32), parameter :: n = 1000
! Local Variables
real(real64), dimension(n) :: x, y1, y2
type(plot_2d) :: plt
type(plot_data_2d) :: d1, d2
class(plot_axis), pointer :: xAxis, yAxis
type(legend), pointer :: lgnd
! Initialize the plot object
call plt%initialize()
! Set plot properties
call plt%set_draw_border(.false.)
call plt%set_show_gridlines(.false.)
! Define the legend location
lgnd => plt%get_legend()
call lgnd%set_is_visible(.true.)
call lgnd%set_draw_inside_axes(.false.)
! Define titles
call plt%set_title("2D Example Plot 2")
xAxis => plt%get_x_axis()
call xAxis%set_title("X Axis")
call xAxis%set_zero_axis(.true.)
call xAxis%set_zero_axis_line_width(1.0)
yAxis => plt%get_y_axis()
call yAxis%set_title("Y Axis")
! Define the data, and then add it to the plot
x = linspace(0.0d0, 10.d0, n)
y1 = sin(5.0d0 * x)
y2 = 2.0d0 * cos(2.0d0 * x)
call d1%define_data(x, y1)
call d2%define_data(x, y2)
! Define properties for each data set
call d1%set_name("Data Set 1")
call d1%set_line_width(1.0)
call d2%set_name("Data Set 2")
call d2%set_line_style(LINE_DASHED)
call d2%set_line_width(2.0)
! Add the data sets to the plot
call plt%push(d1)
call plt%push(d2)
! Let GNUPLOT draw the plot
call plt%draw()
end programThis is the plot resulting from the above program.
The following example illustrates how to create a three-dimensional surface plot. The plot also leverages the FORCOLORMAP library to provide the colormap.
program example
use fplot_core
use iso_fortran_env
use forcolormap, only : colormaps_list
implicit none
! Parameters
integer(int32), parameter :: m = 50
integer(int32), parameter :: n = 50
! Local Variables
real(real64), dimension(m, n, 2), target :: xy
real(real64), pointer, dimension(:,:) :: x, y
real(real64), dimension(m, n) :: z
type(surface_plot) :: plt
type(surface_plot_data) :: d1
class(plot_axis), pointer :: xAxis, yAxis, zAxis
type(custom_colormap) :: map
type(cmap) :: colors
! Set up the colormap
call colors%set("glasgow", -8.0d0, 8.0d0)
call map%set_colormap(colors)
! Define the data
xy = meshgrid(linspace(-5.0d0, 5.0d0, n), linspace(-5.0d0, 5.0d0, m))
x => xy(:,:,1)
y => xy(:,:,2)
! Initialize the plot
call plt%initialize()
call plt%set_colormap(map)
! Establish lighting
call plt%set_use_lighting(.true.)
! Set the orientation of the plot
call plt%set_elevation(20.0d0)
call plt%set_azimuth(30.0d0)
! Define titles
call plt%set_title("Example Plot")
xAxis => plt%get_x_axis()
call xAxis%set_title("X Axis")
yAxis => plt%get_y_axis()
call yAxis%set_title("Y Axis")
zAxis => plt%get_z_axis()
call zAxis%set_title("Z Axis")
! Define the function to plot
z = sqrt(x**2 + y**2) * sin(x**2 + y**2)
call d1%define_data(x, y, z)
call plt%push(d1)
! Draw the plot
call plt%draw()
end programThis is the plot resulting from the above program.
The following example illustrates how to create a vector-field plot. This example illustrates using one of the built-in colormaps to to help illustrate vector magnitude.
program example
use iso_fortran_env
use fplot_core
implicit none
! Local Variables
type(plot_2d) :: plt
type(vector_field_plot_data) :: ds1
class(plot_axis), pointer :: xAxis, yAxis
type(rainbow_colormap) :: cmap
real(real64), allocatable, dimension(:,:,:) :: pts
real(real64), allocatable, dimension(:,:) :: dx, dy
real(real64) :: dxdt(2)
integer(int32) :: i, j
! Create a grid of points defining the vector locations
pts = meshgrid( &
linspace(-2.0d0, 2.0d0, 20), &
linspace(-5.0d0, 5.0d0, 20))
! Compute the values of each derivative
allocate(dx(size(pts, 1), size(pts, 2)))
allocate(dy(size(pts, 1), size(pts, 2)))
do j = 1, size(pts, 2)
do i = 1, size(pts, 1)
call eqn([pts(i,j,1), pts(i,j,2)], dxdt)
dx(i,j) = dxdt(1)
dy(i,j) = dxdt(2)
end do
end do
! Define arrow properties
call ds1%set_arrow_size(0.1d0) ! 1.0 by default
call ds1%set_fill_arrow(.true.) ! .false. by default
! Create the plot
call plt%initialize()
call plt%set_font_size(14)
xAxis => plt%get_x_axis()
yAxis => plt%get_y_axis()
! Define axis labels
call xAxis%set_title("x(t)")
call yAxis%set_title("dx/dt")
! Set plot style information
call xAxis%set_zero_axis(.true.)
call yAxis%set_zero_axis(.true.)
call plt%set_draw_border(.false.)
call plt%set_show_gridlines(.false.)
! Define the colormap
call plt%set_colormap(cmap)
! Add the data to the plot - color by the magnitude of gradient
call ds1%define_data(pts(:,:,1), pts(:,:,2), dx, dy, sqrt(dx**2 + dy**2))
call plt%push(ds1)
call plt%draw()
contains
! Van der Pol Equation
! x" - mu * (1 - x^2) * x' + x = 0
subroutine eqn(x, dxdt)
real(real64), intent(in) :: x(2)
real(real64), intent(out) :: dxdt(2)
real(real64), parameter :: mu = 2.0d0
dxdt(1) = x(2)
dxdt(2) = mu * (1.0d0 - x(1)**2) * x(2) - x(1)
end subroutine
end programThis is the plot resulting from the above program.
The following example illustrates how to create a polar plot.
program example
use iso_fortran_env
use fplot_core
! Local Variables
integer(int32), parameter :: npts = 1000
real(real64), parameter :: pi = 2.0d0 * acos(0.0d0)
real(real64) :: t(npts), x(npts)
type(plot_polar) :: plt
type(plot_data_2d) :: pd
! Create a function to plot
t = linspace(-2.0d0 * pi, 2.0d0 * pi, npts)
x = t * sin(t)
! Plot the function
call plt%initialize()
call plt%set_font_size(14)
call plt%set_title("Polar Plot Example")
call plt%set_autoscale(.false.)
call plt%set_radial_limits([0.0d0, 6.0d0])
call pd%define_data(t, x)
call pd%set_line_width(2.0)
call plt%push(pd)
call plt%draw()
end programThis is the plot resulting from the above program.
