Usage

use fortplot

Stateful API

use fortplot  ! Provides wp=> real64 for precisionreal(wp),dimension(50):: x, y! Generate sampledatax= [(real(i-1, wp)*0.2_wp, i=1,50)]y=sin(x)call figure()call plot(x, y)call title("Function Plot")call xlabel("x")call ylabel("y")call xlim(0.0_wp,10.0_wp)  ! Set x-axis limitscall ylim(-1.0_wp,1.0_wp)   ! Set y-axis limitscall savefig("plot.png")

Note: Subplot Grids (Not Yet Implemented)

! Multiple subplots are not yet implemented.! Calling subplot(...) currently emits a warning ("subplot: Multiple! subplots not yet implemented") and only the first panel is! rendered/saved. This feature is planned for a future release.call figure(figsize=[8.0_wp,6.0_wp])call subplot(2,2,1)  ! Will show warningcall plot(x,sin(x))call title("Sine Wave")call savefig("single_plot.png")  ! Only first subplot will be saved

Object-Oriented API

use fortplot  ! Imports wp=> real64 for precisiontype(figure_t):: figreal(wp),dimension(50):: x, yfinteger:: i! Generate testdatax= [(real(i-1, wp)*0.1_wp, i=1,50)]yf=sin(x)call fig%initialize()call fig%set_title("Function Plot")call fig%set_xlabel("x")call fig%set_ylabel("y")call fig%add_plot(x, yf)call fig%savefig("plot_oo.png")

Advanced Examples

3D plotting

call figure(figsize=[8.0_wp,6.0_wp])call add_3d_plot(x, y, z, label="3D curve")call title("3D Line Plot")call savefig("3d_plot.png")

Multiple plots with legend

call figure(figsize=[8.0_wp,6.0_wp])call plot(x,sin(x), label="sin(x)", linestyle="b-")call plot(x,cos(x), label="cos(x)", linestyle="r--")call plot(x,sin(2*x), label="sin(2x)", linestyle="g:")call legend()call savefig("trig_functions.pdf")

Unicode and Greek letters in scientific plots

call figure(figsize=[8.0_wp,6.0_wp])call title("Wave Functions: \psi(\omega t) = A e^{-\lambda t} sin(\omega t)")call xlabel("Time \tau (normalized)")call ylabel("Amplitude \Psi (V)")call plot(t, damped_sine, label="\alpha decay")call plot(t, damped_cosine, label="\beta oscillation")call legend()call savefig("unicode_demo.png")  ! Worksin PNG, PDF, and ASCII

Enhanced scatter plots with size/color mapping

! Basic scatter plotcall figure()call scatter(x, y, label="Data Points")call savefig("basic_scatter.png")! Object-oriented scatter plottype(figure_t):: figreal(wp),dimension(20):: x, y, sizescall fig%initialize()call fig%scatter(x, y, label='Bubble Chart')call fig%savefig("bubble_chart.pdf")

Surface plots (3D visualization)

use fortplotimplicit nonereal(wp),dimension(50):: x, y, zinteger:: i! Generate3D curvedatax= [(real(i-1, wp)*0.1_wp, i=1,50)]y=sin(x)z=cos(x)!3D surface visualizationcall figure(figsize=[8.0_wp,6.0_wp])call add_3d_plot(x, y, z, label="3D Surface Curve")call title("3D Surface Plot")call savefig("surface_3d.png")! pcolormesh for2D heatmaps is available and working! Array dimensions: z(ny,nx) with x(nx+1), y(ny+1) is the! standard scientificformat and does NOT emit warnings.! C-style z(nx,ny) is also accepted; it is transposed internally.real(wp),dimension(10,10):: z_data  ! ny=10, nx=10call pcolormesh(x_grid, y_grid, z_data, colormap="viridis")

Contour plot with colorbar

call figure()call contour_filled(x_grid, y_grid, z_data, colormap="viridis", show_colorbar=.true.)call title("Temperature Distribution")call xlabel("X Position")call ylabel("Y Position")call savefig("temperature.png")

Streamplot with arrows

! Basic streamplot with default arrowscall figure()call streamplot(x_grid, y_grid, u_field, v_field)call savefig("flow_field.png")! Streamplot with custom arrow size and stylecall streamplot(x_grid, y_grid, u_field, v_field, arrowsize=1.5_real64, arrowstyle='<->')! Streamlines without arrowscall streamplot(x_grid, y_grid, u_field, v_field, arrowsize=0.0_real64)

Error bars for scientific data

use fortplot  ! Imports wp=> real64 automaticallyimplicit none! Use functional API for errorbar plots (currently supported)real(wp),dimension(20):: x, y, yerr, y_theorycall figure(figsize=[8.0_wp,6.0_wp])call errorbar(x, y, yerr=yerr, marker='o', label='Experimental data')call plot(x, y_theory, label='Theory', linestyle='-')call legend()call savefig("scientific_plot.png")

Log scale plot

call figure()call plot(x, y)call set_xscale("log")call set_yscale("symlog", threshold=0.01_wp)call xlim(1.0e-3_wp,1.0e3_wp)call ylim(-100.0_wp,100.0_wp)call savefig("log_plot.pdf")

Build, Test, and Artifact Verification

Artifact Verification (required for rendering changes)

Python Example Outputs

make example_python_dual# or per-examplepython3 example/python/basic_plots/basic_plots.py# fortplotpython3 example/python/basic_plots/basic_plots.py --matplotlib# matplotlib

Text annotations with coordinate systems

! Text annotation system is FULLY IMPLEMENTEDuse fortplottype(figure_t):: figreal(wp),dimension(50):: x, yinteger:: i! Generate sampledatax= [(real(i-1, wp)*0.1_wp, i=1,50)]y=sin(x)call figure(figsize=[8.0_wp,6.0_wp])call add_plot(x, y, label="Scientific Data", linestyle="b-")call set_title("Annotated Scientific Plot")call set_xlabel("X Variable")call set_ylabel("Y Variable")! Add text annotations with different coordinate systemscall add_text_annotation("Maximum",1.57_wp,1.0_wp, coord_type=COORD_DATA)call add_arrow_annotation("Peak→",1.2_wp,0.8_wp,1.57_wp,1.0_wp, coord_type=COORD_DATA)call add_text_annotation("Title Area",0.5_wp,0.95_wp, coord_type=COORD_FIGURE)call savefig("annotated_plot.png")

Animation example

use fortplot_animationtype(figure_t):: figtype(animation_t):: animinteger:: statusreal(wp),dimension(100):: x_data, y_data! Setup figure and initial plotcall figure(figsize=[8.0_wp,6.0_wp])call add_plot(x_data, y_data, label='animated data')call title('Animation Demo')! Create animation with update functionanim= FuncAnimation(update_frame, frames=100, interval=50, fig=fig)call save_animation(anim,"animation.mp4",24, status)if (status/=0)thenprint*,"ERROR: Animation save failed. Check ffmpeg installation."print*,"Windows: choco install ffmpeg"print*,"Linux: sudo apt install ffmpeg"end ifcontainssubroutineupdate_frame(frame)integer,intent(in):: frame        ! Update plotdata based on frame numbercall set_ydata(sin(x_data+real(frame, wp)*0.1_wp))endsubroutine update_frame

make example

Setup

Dependencies

For fpm (Fortran Package Manager) projects

[[dependencies]]fortplot = {git ="https://github.com/lazy-fortran/fortplot" }

For CMake projects

include(FetchContent)FetchContent_Declare(    fortplot    GIT_REPOSITORY https://github.com/lazy-fortran/fortplot    GIT_TAG        main)FetchContent_MakeAvailable(fortplot)target_link_libraries(your_target fortplot::fortplot)

Security Features

Verify Security Compliance

# Build with trampoline detection enabled# Requires Ninja generator (install package: ninja or ninja-build)cmake -S. -B build -G Ninja&& cmake --build build -j# Library builds successfully = trampoline-free core code# Verify no executable stack segmentsreadelf -W -l build/libfortplot.a| grep -i stack# Should return empty (no executable stack)# Test trampoline detection (should fail on example with nested function)fpm build --flag"-Werror=trampolines"2>/dev/null||echo"Trampoline detection working"# Error confirms security validation is active

Security Build Flags

# FPM: Manual security flags (as documented in fpm.toml)fpm build --flag"-Wtrampolines -Werror=trampolines"# CMake: Automatic security flags (see CMakeLists.txt lines 36-47)cmake -S. -B build -G Ninja&& cmake --build build -j# Standard development (FPM default)make build# Uses fpm.toml configuration

For Python projects

pip install git+https://github.com/lazy-fortran/fortplot.git

Features

Plot types

Backends

Features

Module Architecture

! Your existing code works unchangeduse fortplot_pdf, only: pdf_context, create_pdf_canvastype(pdf_context):: ctxcall create_pdf_canvas(ctx,"plot.pdf",800,600)

Testing

Run Tests

maketest

Complexity Budgets (Issue #937)

# Verify heuristic procedure count budgetsmake verify-complexity# Optional: override budgetsMAX_TOTAL_PROCS=1800 MAX_PROCS_PER_FILE=50 make verify-complexity

Control Warning Output

# Suppress warnings for clean test outputFORTPLOT_SUPPRESS_WARNINGS=1 maketest# Force warnings even in CI environmentsFORTPLOT_FORCE_WARNINGS=1 maketest

Documentation Generation

make doc

Branch Naming & Lifecycle

# Dry-run: see what would be prunedmake git-prune# Apply pruning (removes merged local branches older than 30 days)make git-prune FORCE=1

Why though?

time make example_matplotlib5.13s user 0.52s system 91% cpu 6.159 totaltime make example_python1.35s user 0.17s system 97% cpu 1.562 total