program legend_demo !! Demonstration of legend functionality following SOLID principles !! Shows legend positioning, labeling, and rendering across all backends use fortplot use, intrinsic :: iso_fortran_env, only: wp => real64 implicit none call basic_legend_example() call positioned_legend_example() call multi_function_legend_example() call legend_box_styling_example() contains subroutine basic_legend_example() !! Basic legend usage with labeled plots real(wp), dimension(50) :: x, y1, y2 integer :: i print *, "=== Basic Legend Example ===" ! Generate data x = [(real(i-1, wp) * 0.2_wp, i=1, 50)] y1 = sin(x) y2 = cos(x) call figure(figsize=[8.0_wp, 6.0_wp]) call title("Basic Legend Demo") call xlabel("x") call ylabel("y") ! Add labeled plots call add_plot(x, y1, label="sin(x)") call add_plot(x, y2, label="cos(x)") ! Add legend with default position (upper right) call legend() call savefig('output/example/fortran/legend_demo/basic_legend.png') call savefig('output/example/fortran/legend_demo/basic_legend.pdf') call savefig('output/example/fortran/legend_demo/basic_legend.txt') print *, "Created: basic_legend.png/pdf/txt" end subroutine basic_legend_example subroutine positioned_legend_example() !! Demonstrate different legend positions real(wp), dimension(20) :: x, y1, y2 integer :: i print *, "=== Legend Positioning Examples ===" ! Generate test data x = [(real(i, wp), i=1, 20)] y1 = x**0.5_wp y2 = log(x) ! Upper left position ! NOTE: figsize units are in inches (like matplotlib), not pixels call figure(figsize=[6.4_wp, 4.8_wp]) call title("Legend: Upper Left") call add_plot(x, y1, label="√x") call add_plot(x, y2, label="ln(x)") call legend(position="upper left") call savefig('output/example/fortran/legend_demo/legend_upper_left.png') call savefig('output/example/fortran/legend_demo/legend_upper_left.pdf') call savefig('output/example/fortran/legend_demo/legend_upper_left.txt') ! Upper right position (default) call figure(figsize=[6.4_wp, 4.8_wp]) call title("Legend: Upper Right") call add_plot(x, y1, label="√x") call add_plot(x, y2, label="ln(x)") call legend(position="upper right") call savefig('output/example/fortran/legend_demo/legend_upper_right.png') call savefig('output/example/fortran/legend_demo/legend_upper_right.pdf') call savefig('output/example/fortran/legend_demo/legend_upper_right.txt') ! Lower left position call figure(figsize=[6.4_wp, 4.8_wp]) call title("Legend: Lower Left") call add_plot(x, y1, label="√x") call add_plot(x, y2, label="ln(x)") call legend(position="lower left") call savefig('output/example/fortran/legend_demo/legend_lower_left.png') call savefig('output/example/fortran/legend_demo/legend_lower_left.pdf') call savefig('output/example/fortran/legend_demo/legend_lower_left.txt') ! Lower right position call figure(figsize=[6.4_wp, 4.8_wp]) call title("Legend: Lower Right") call add_plot(x, y1, label="√x") call add_plot(x, y2, label="ln(x)") call legend(position="lower right") call savefig('output/example/fortran/legend_demo/legend_lower_right.png') call savefig('output/example/fortran/legend_demo/legend_lower_right.pdf') call savefig('output/example/fortran/legend_demo/legend_lower_right.txt') print *, "Created: legend_upper_left/right.png/pdf/txt, legend_lower_left/right.png/pdf/txt" end subroutine positioned_legend_example subroutine multi_function_legend_example() !! Complex legend with multiple mathematical functions real(wp), dimension(100) :: x, y1, y2, y3, y4 integer :: i print *, "=== Multi-Function Legend Example ===" ! Generate mathematical functions x = [(real(i-1, wp) * 0.1_wp, i=1, 100)] y1 = exp(-x/2.0_wp) * cos(x) y2 = x * exp(-x/3.0_wp) ! Avoid division by zero at x=0: define sin(x)/x = 1 at x=0 where (x == 0.0_wp) y3 = 1.0_wp elsewhere y3 = sin(x) / x end where y4 = x**2 * exp(-x) call figure(figsize=[8.0_wp, 6.0_wp]) call title("Mathematical Functions with Legend") call xlabel("x") call ylabel("f(x)") ! Add multiple labeled functions ! Use mathtext with braces for multi-character superscripts call add_plot(x, y1, label="$e^{-x/2}cos(x)$") call add_plot(x, y2, label="$xe^{-x/3}$") call add_plot(x, y3, label="$sin(x)/x$") call add_plot(x, y4, label="$x^{2}e^{-x}$") ! Add legend call legend() call savefig('output/example/fortran/legend_demo/multi_function_legend.png') call savefig('output/example/fortran/legend_demo/multi_function_legend.pdf') call savefig('output/example/fortran/legend_demo/multi_function_legend.txt') print *, "Created: multi_function_legend.png/pdf/txt" end subroutine multi_function_legend_example subroutine legend_box_styling_example() !! Demonstrate legend box styling and multiple entries real(wp), dimension(50) :: x, y1, y2, y3, y4 integer :: i print *, "=== Legend Box Styling Example ===" ! Generate test data with multiple functions x = [(real(i-1, wp) / 49.0_wp * 2.0_wp * 3.14159_wp, i=1, 50)] y1 = sin(x) y2 = y1 * 0.5_wp y3 = cos(x) * 0.7_wp y4 = -y1 * 0.3_wp call figure(figsize=[8.0_wp, 6.0_wp]) call title("Legend Box Styling Demo") call xlabel("x") call ylabel("y") ! Add multiple plots to test legend box styling call add_plot(x, y1, label="sin(x)") call add_plot(x, y2, label="0.5 sin(x)") call add_plot(x, y3, label="0.7 cos(x)") call add_plot(x, y4, label="-0.3 sin(x)") ! Test legend box with default styling call legend() call savefig('output/example/fortran/legend_demo/legend_box_default.png') call savefig('output/example/fortran/legend_demo/legend_box_default.pdf') call savefig('output/example/fortran/legend_demo/legend_box_default.txt') ! Test legend box in different positions call legend(position="upper left") call savefig('output/example/fortran/legend_demo/legend_box_upper_left.png') call savefig('output/example/fortran/legend_demo/legend_box_upper_left.pdf') call savefig('output/example/fortran/legend_demo/legend_box_upper_left.txt') call legend(position="lower right") call savefig('output/example/fortran/legend_demo/legend_box_lower_right.png') call savefig('output/example/fortran/legend_demo/legend_box_lower_right.pdf') call savefig('output/example/fortran/legend_demo/legend_box_lower_right.txt') print *, "Created: legend_box_default.png/pdf/txt, legend_box_upper_left.png/pdf/txt, legend_box_lower_right.png/pdf/txt" end subroutine legend_box_styling_example end program legend_demo