Use eachindex instead of 1:length, compare against nothing with ===

docs/literate/src/files/non_periodic_boundaries.jl

@@ -99,7 +99,7 @@ sol = solve(ode, CarpenterKennedy2N54(williamson_condition=false),
             save_everystep=false, saveat=visnodes, callback=callbacks);
 
 using Plots
-@gif for step in 1:length(sol.u)
+@gif for step in eachindex(sol.u)
     plot(sol.u[step], semi, ylim=(-1.5, 1.5), legend=true, label="approximation", title="time t=$(round(sol.t[step], digits=5))")
     scatter!([0.0], [sum(boundary_condition(SVector(0.0), sol.t[step], equations))], label="boundary condition")
 end

docs/literate/src/files/scalar_linear_advection_1d.jl

@@ -120,7 +120,7 @@ integral = sum(nodes.^3 .* weights)
 x = Matrix{Float64}(undef, length(nodes), n_elements)
 for element in 1:n_elements
     x_l = coordinates_min + (element - 1) * dx + dx/2
-    for i in 1:length(nodes)
+    for i in eachindex(nodes)
         ξ = nodes[i] # nodes in [-1, 1]
         x[i, element] = x_l + dx/2 * ξ
     end
@@ -417,7 +417,7 @@ dx = (coordinates_max - coordinates_min) / n_elements # length of one element
 x = Matrix{Float64}(undef, length(nodes), n_elements)
 for element in 1:n_elements
     x_l = -1 + (element - 1) * dx + dx/2
-    for i in 1:length(nodes) # basis points in [-1, 1]
+    for i in eachindex(nodes) # basis points in [-1, 1]
         ξ = nodes[i]
         x[i, element] = x_l + dx/2 * ξ
     end

examples/p4est_2d_dgsem/elixir_advection_amr_solution_independent.jl

@@ -33,7 +33,7 @@ function (indicator::IndicatorSolutionIndependent)(u::AbstractArray{<:Any, 4},
     outer_distance = 1.85
 
     #Iterate over all elements
-    for element in 1:length(alpha)
+    for element in eachindex(alpha)
         # Calculate periodic distance between cell and center.
         # This requires an uncurved mesh!
         coordinates = SVector(0.5 * (cache.elements.node_coordinates[1, 1, 1, element] +

examples/t8code_2d_dgsem/elixir_advection_amr_solution_independent.jl

@@ -32,7 +32,7 @@ function (indicator::IndicatorSolutionIndependent)(u::AbstractArray{<:Any, 4},
     outer_distance = 1.85
 
     # Iterate over all elements.
-    for element in 1:length(alpha)
+    for element in eachindex(alpha)
         # Calculate periodic distance between cell and center.
         # This requires an uncurved mesh!
         coordinates = SVector(0.5 * (cache.elements.node_coordinates[1, 1, 1, element] +

examples/tree_2d_dgsem/elixir_advection_amr_solution_independent.jl

@@ -31,7 +31,7 @@ function (indicator::IndicatorSolutionIndependent)(u::AbstractArray{<:Any, 4},
     outer_distance = 1.85
 
     #Iterate over all elements
-    for element in 1:length(alpha)
+    for element in eachindex(alpha)
         #Calculate periodic distance between cell and center.
         cell_id = cache.elements.cell_ids[element]
         coordinates = mesh.tree.coordinates[1:2, cell_id]

src/callbacks_step/amr.jl

@@ -243,7 +243,7 @@ function (amr_callback::AMRCallback)(u_ode::AbstractVector, mesh::TreeMesh,
     @unpack to_refine, to_coarsen = amr_callback.amr_cache
     empty!(to_refine)
     empty!(to_coarsen)
-    for element in 1:length(lambda)
+    for element in eachindex(lambda)
         controller_value = lambda[element]
         if controller_value > 0
             push!(to_refine, leaf_cell_ids[element])
@@ -307,7 +307,7 @@ function (amr_callback::AMRCallback)(u_ode::AbstractVector, mesh::TreeMesh,
         end
 
         # Extract only those parent cells for which all children should be coarsened
-        to_coarsen = collect(1:length(parents_to_coarsen))[parents_to_coarsen .== 2^ndims(mesh)]
+        to_coarsen = collect(eachindex(parents_to_coarsen))[parents_to_coarsen .== 2^ndims(mesh)]
 
         # Finally, coarsen mesh
         coarsened_original_cells = @trixi_timeit timer() "mesh" coarsen!(mesh.tree,
@@ -395,7 +395,7 @@ function (amr_callback::AMRCallback)(u_ode::AbstractVector, mesh::TreeMesh,
     @unpack to_refine, to_coarsen = amr_callback.amr_cache
     empty!(to_refine)
     empty!(to_coarsen)
-    for element in 1:length(lambda)
+    for element in eachindex(lambda)
         controller_value = lambda[element]
         if controller_value > 0
             push!(to_refine, leaf_cell_ids[element])
@@ -456,7 +456,7 @@ function (amr_callback::AMRCallback)(u_ode::AbstractVector, mesh::TreeMesh,
         end
 
         # Extract only those parent cells for which all children should be coarsened
-        to_coarsen = collect(1:length(parents_to_coarsen))[parents_to_coarsen .== 2^ndims(mesh)]
+        to_coarsen = collect(eachindex(parents_to_coarsen))[parents_to_coarsen .== 2^ndims(mesh)]
 
         # Finally, coarsen mesh
         coarsened_original_cells = @trixi_timeit timer() "mesh" coarsen!(mesh.tree,

src/callbacks_step/euler_acoustics_coupling_dg2d.jl

@@ -12,7 +12,7 @@ function calc_acoustic_sources!(acoustic_source_terms, u_euler, u_acoustics,
                                 dg::DGSEM, cache)
     acoustic_source_terms .= zero(eltype(acoustic_source_terms))
 
-    @threaded for k in 1:length(coupled_element_ids)
+    @threaded for k in eachindex(coupled_element_ids)
         element = coupled_element_ids[k]
 
         for j in eachnode(dg), i in eachnode(dg)

src/callbacks_step/time_series_dg_tree.jl

@@ -25,7 +25,7 @@ function get_elements_by_coordinates!(element_ids, coordinates, mesh::TreeMesh,
         cell_id = cell_ids[element]
 
         # Iterate over coordinates
-        for index in 1:length(element_ids)
+        for index in eachindex(element_ids)
             # Skip coordinates for which an element has already been found
             if element_ids[index] > 0
                 continue
@@ -63,7 +63,7 @@ function calc_interpolating_polynomials!(interpolating_polynomials, coordinates,
 
     wbary = barycentric_weights(nodes)
 
-    for index in 1:length(element_ids)
+    for index in eachindex(element_ids)
         # Construct point
         x = SVector(ntuple(i -> coordinates[i, index], ndims(mesh)))
 
@@ -94,7 +94,7 @@ function record_state_at_points!(point_data, u, solution_variables,
     new_length = old_length + n_solution_variables
 
     # Loop over all points/elements that should be recorded
-    for index in 1:length(element_ids)
+    for index in eachindex(element_ids)
         # Extract data array and element id
         data = point_data[index]
         element_id = element_ids[index]
@@ -108,7 +108,7 @@ function record_state_at_points!(point_data, u, solution_variables,
             u_node = solution_variables(get_node_vars(u, equations, dg, i,
                                                       element_id), equations)
 
-            for v in 1:length(u_node)
+            for v in eachindex(u_node)
                 data[old_length + v] += (u_node[v] *
                                          interpolating_polynomials[i, 1, index])
             end
@@ -126,7 +126,7 @@ function record_state_at_points!(point_data, u, solution_variables,
     new_length = old_length + n_solution_variables
 
     # Loop over all points/elements that should be recorded
-    for index in 1:length(element_ids)
+    for index in eachindex(element_ids)
         # Extract data array and element id
         data = point_data[index]
         element_id = element_ids[index]
@@ -140,7 +140,7 @@ function record_state_at_points!(point_data, u, solution_variables,
             u_node = solution_variables(get_node_vars(u, equations, dg, i, j,
                                                       element_id), equations)
 
-            for v in 1:length(u_node)
+            for v in eachindex(u_node)
                 data[old_length + v] += (u_node[v]
                                          * interpolating_polynomials[i, 1, index]
                                          * interpolating_polynomials[j, 2, index])
@@ -159,7 +159,7 @@ function record_state_at_points!(point_data, u, solution_variables,
     new_length = old_length + n_solution_variables
 
     # Loop over all points/elements that should be recorded
-    for index in 1:length(element_ids)
+    for index in eachindex(element_ids)
         # Extract data array and element id
         data = point_data[index]
         element_id = element_ids[index]
@@ -173,7 +173,7 @@ function record_state_at_points!(point_data, u, solution_variables,
             u_node = solution_variables(get_node_vars(u, equations, dg, i, j, k,
                                                       element_id), equations)
 
-            for v in 1:length(u_node)
+            for v in eachindex(u_node)
                 data[old_length + v] += (u_node[v]
                                          * interpolating_polynomials[i, 1, index]
                                          * interpolating_polynomials[j, 2, index]

src/callbacks_step/time_series_dg_unstructured.jl

@@ -31,7 +31,7 @@ function get_elements_by_coordinates!(element_ids, coordinates,
     # Iterate over coordinates
     distances = zeros(eltype(mesh.corners), mesh.n_elements)
     indices = zeros(Int, mesh.n_elements, 2)
-    for index in 1:length(element_ids)
+    for index in eachindex(element_ids)
         # Grab the current point for which the element needs found
         point = SVector(coordinates[1, index],
                         coordinates[2, index])
@@ -77,7 +77,7 @@ function get_elements_by_coordinates!(element_ids, coordinates,
         # Loop through all the element candidates until we find a vector from the barycenter
         # to the surface that points in the same direction as the current `point` vector.
         # This then gives us the correct element.
-        for element in 1:length(candidates)
+        for element in eachindex(candidates)
             bary_center = SVector(bary_centers[1, candidates[element]],
                                   bary_centers[2, candidates[element]])
             # Vector pointing from the barycenter toward the minimal `surface_point`
@@ -118,7 +118,7 @@ function calc_minimum_surface_distance(point, node_coordinates,
     n = nnodes(dg)
     min_distance2 = Inf * ones(eltype(mesh.corners), length(mesh))
     indices = zeros(Int, length(mesh), 2)
-    for k in 1:length(mesh)
+    for k in eachindex(mesh)
         # used to ensure that only boundary points are used
         on_surface = MVector(false, false)
         for j in 1:n
@@ -153,7 +153,7 @@ function calc_interpolating_polynomials!(interpolating_polynomials, coordinates,
     # Helper array for a straight-sided quadrilateral element
     corners = zeros(eltype(mesh.corners), 4, 2)
 
-    for index in 1:length(element_ids)
+    for index in eachindex(element_ids)
         # Construct point
         x = SVector(ntuple(i -> coordinates[i, index], ndims(mesh)))
 
@@ -280,7 +280,7 @@ function record_state_at_points!(point_data, u, solution_variables,
     new_length = old_length + n_solution_variables
 
     # Loop over all points/elements that should be recorded
-    for index in 1:length(element_ids)
+    for index in eachindex(element_ids)
         # Extract data array and element id
         data = point_data[index]
         element_id = element_ids[index]
@@ -294,7 +294,7 @@ function record_state_at_points!(point_data, u, solution_variables,
             u_node = solution_variables(get_node_vars(u, equations, dg, i, j,
                                                       element_id), equations)
 
-            for v in 1:length(u_node)
+            for v in eachindex(u_node)
                 data[old_length + v] += (u_node[v]
                                          * interpolating_polynomials[i, 1, index]
                                          * interpolating_polynomials[j, 2, index])

src/semidiscretization/semidiscretization_euler_acoustics.jl

@@ -103,7 +103,7 @@ function precompute_weights(source_region, weights, coupled_element_ids, equatio
                                     (nnodes(dg), nnodes(dg),
                                      length(coupled_element_ids)))
 
-    @threaded for k in 1:length(coupled_element_ids)
+    @threaded for k in eachindex(coupled_element_ids)
         element = coupled_element_ids[k]
         for j in eachnode(dg), i in eachnode(dg)
             x = get_node_coords(cache.elements.node_coordinates, equations, dg, i, j,
@@ -197,7 +197,7 @@ function add_acoustic_source_terms!(du_acoustics, acoustic_source_terms, source_
                                     coupled_element_ids, mesh::TreeMesh{2}, equations,
                                     dg::DGSEM,
                                     cache)
-    @threaded for k in 1:length(coupled_element_ids)
+    @threaded for k in eachindex(coupled_element_ids)
         element = coupled_element_ids[k]
 
         for j in eachnode(dg), i in eachnode(dg)

src/visualization/utilities.jl

@@ -495,7 +495,7 @@ function cell2node(cell_centered_data)
     resolution_in, _ = size(first(cell_centered_data))
     resolution_out = resolution_in + 1
     node_centered_data = [Matrix{Float64}(undef, resolution_out, resolution_out)
-                          for _ in 1:length(cell_centered_data)]
+                          for _ in eachindex(cell_centered_data)]
 
     for (cell_data, node_data) in zip(cell_centered_data, node_centered_data)
         # Fill center with original data
@@ -1545,7 +1545,7 @@ end
 
 # Create an axis.
 function axis_curve(nodes_x, nodes_y, nodes_z, slice, point, n_points)
-    if n_points == nothing
+    if n_points === nothing
         n_points = 64
     end
     dimensions = length(point)

test/test_unit.jl

@@ -284,7 +284,7 @@ end
     function MyContainer(data, capacity)
         c = MyContainer(Vector{Int}(undef, capacity + 1), capacity, length(data),
                         capacity + 1)
-        c.data[1:length(data)] .= data
+        c.data[eachindex(data)] .= data
         return c
     end
     MyContainer(data::AbstractArray) = MyContainer(data, length(data))

utils/trixi2txt.jl

@@ -86,7 +86,7 @@ function trixi2txt(filename::AbstractString...;
                   "maximum supported level $max_supported_level")
         end
         max_available_nodes_per_finest_element = 2^(max_supported_level - max_level)
-        if nvisnodes == nothing
+        if nvisnodes === nothing
             max_nvisnodes = 2 * n_nodes
         elseif nvisnodes == 0
             max_nvisnodes = n_nodes
@@ -137,9 +137,9 @@ function trixi2txt(filename::AbstractString...;
             println(io)
 
             # Data
-            for idx in 1:length(xs)
+            for idx in eachindex(xs)
                 @printf(io, "%+10.8e", xs[idx])
-                for variable_id in 1:length(variables)
+                for variable_id in eachindex(variables)
                     @printf(io, " %+10.8e ", node_centered_data[idx, variable_id])
                 end
                 println(io)
@@ -199,7 +199,7 @@ function read_meshfile(filename::String)
         # Extract leaf cells (= cells to be plotted) and contract all other arrays accordingly
         leaf_cells = similar(levels)
         n_cells = 0
-        for cell_id in 1:length(levels)
+        for cell_id in eachindex(levels)
             if sum(child_ids[:, cell_id]) > 0
                 continue
             end