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visualize_isochrone(graph_name=None, source_node=None, max_solution_radius=-1.0, weights_on_edges=[], restrictions=[], num_levels=1, generate_image=True, levels_table=”, style_options=None, solve_options=, contour_options=, options=)[source]

Generate an image containing isolines for travel results using an existing graph. Isolines represent curves of equal cost, with cost typically referring to the time or distance assigned as the weights of the underlying graph. See Graphs and Solvers for more information on graphs.

Parameters

graph_name (str) –

Name of the graph on which the isochrone is to be computed.

source_node (str) –

Starting vertex on the underlying graph from/to which the isochrones are created.

max_solution_radius (float) –

Extent of the search radius around input parameter source_node. Set to ‘-1.0’ for unrestricted search radius. The default value is -1.0.

weights_on_edges (list of str) –

Additional weights to apply to the edges of an existing graph. Weights must be specified using identifiers; identifiers are grouped as combinations. Identifiers can be used with existing column names, e.g., ‘table.column AS WEIGHTS_EDGE_ID’, or expressions, e.g., ‘ST_LENGTH(wkt) AS WEIGHTS_VALUESPECIFIED’. Any provided weights will be added (in the case of ‘WEIGHTS_VALUESPECIFIED’) to or multiplied with (in the case of ‘WEIGHTS_FACTORSPECIFIED’) the existing weight(s). The default value is an empty list ( [] ). The user can provide a single element (which will be automatically promoted to a list internally) or a list.

restrictions (list of str) –

Additional restrictions to apply to the nodes/edges of an existing graph. Restrictions must be specified using identifiers; identifiers are grouped as combinations. Identifiers can be used with existing column names, e.g., ‘table.column AS RESTRICTIONS_EDGE_ID’, or expressions, e.g., ‘column/2 AS RESTRICTIONS_VALUECOMPARED’. If remove_previous_restrictions is set to true, any provided restrictions will replace the existing restrictions. If remove_previous_restrictions is set to false, any provided restrictions will be added (in the case of ‘RESTRICTIONS_VALUECOMPARED’) to or replaced (in the case of ‘RESTRICTIONS_ONOFFCOMPARED’). The default value is an empty list ( [] ). The user can provide a single element (which will be automatically promoted to a list internally) or a list.

num_levels (int) –

Number of equally-separated isochrones to compute. The default value is 1.

generate_image (bool) –

If set to true, generates a PNG image of the isochrones in the response. Allowed values are:

  • True

  • False

The default value is True.

levels_table (str) –

Name of the table to output the isochrones to, in [schema_name.]table_name format, using standard name resolution rules and meeting table naming criteria. The table will contain levels and their corresponding WKT geometry. If no value is provided, the table is not generated. The default value is ‘’.

style_options (dict of str to str) –

Various style related options of the isochrone image. Allowed keys are:

  • line_size – The width of the contour lines in pixels. The default value is ‘3’. The minimum allowed value is ‘0’. The maximum allowed value is ‘20’.

  • color – Color of generated isolines. All color values must be in the format RRGGBB or AARRGGBB (to specify the alpha value). If alpha is specified and flooded contours are enabled, it will be used for as the transparency of the latter. The default value is ‘FF696969’.

  • bg_color – When input parameter generate_image is set to true, background color of the generated image. All color values must be in the format RRGGBB or AARRGGBB (to specify the alpha value). The default value is ‘00000000’.

  • text_color – When add_labels is set to true, color for the labels. All color values must be in the format RRGGBB or AARRGGBB (to specify the alpha value). The default value is ‘FF000000’.

  • colormap – Colormap for contours or fill-in regions when applicable. All color values must be in the format RRGGBB or AARRGGBB (to specify the alpha value). Allowed values are:

    • jet

    • accent

    • afmhot

    • autumn

    • binary

    • blues

    • bone

    • brbg

    • brg

    • bugn

    • bupu

    • bwr

    • cmrmap

    • cool

    • coolwarm

    • copper

    • cubehelix

    • dark2

    • flag

    • gist_earth

    • gist_gray

    • gist_heat

    • gist_ncar

    • gist_rainbow

    • gist_stern

    • gist_yarg

    • gnbu

    • gnuplot2

    • gnuplot

    • gray

    • greens

    • greys

    • hot

    • hsv

    • inferno

    • magma

    • nipy_spectral

    • ocean

    • oranges

    • orrd

    • paired

    • pastel1

    • pastel2

    • pink

    • piyg

    • plasma

    • prgn

    • prism

    • pubu

    • pubugn

    • puor

    • purd

    • purples

    • rainbow

    • rdbu

    • rdgy

    • rdpu

    • rdylbu

    • rdylgn

    • reds

    • seismic

    • set1

    • set2

    • set3

    • spectral

    • spring

    • summer

    • terrain

    • viridis

    • winter

    • wistia

    • ylgn

    • ylgnbu

    • ylorbr

    • ylorrd

    The default value is ‘jet’.

solve_options (dict of str to str) –

Solver specific parameters. Allowed keys are:

  • remove_previous_restrictions – Ignore the restrictions applied to the graph during the creation stage and only use the restrictions specified in this request if set to true. Allowed values are:

    • true

    • false

    The default value is ‘false’.

  • restriction_threshold_value – Value-based restriction comparison. Any node or edge with a ‘RESTRICTIONS_VALUECOMPARED’ value greater than the restriction_threshold_value will not be included in the solution.

  • uniform_weights – When specified, assigns the given value to all the edges in the graph. Note that weights provided in input parameter weights_on_edges will override this value.

The default value is an empty dict ( ).

contour_options (dict of str to str) –

Contour specific parameters. Allowed keys are:

  • projection – Spatial Reference System (i.e. EPSG Code). Allowed values are:

    • 3857

    • 102100

    • 900913

    • EPSG:4326

    • PLATE_CARREE

    • EPSG:900913

    • EPSG:102100

    • EPSG:3857

    • WEB_MERCATOR

    The default value is ‘PLATE_CARREE’.

  • width – When input parameter generate_image is set to true, width of the generated image. The default value is ‘512’.

  • height – When input parameter generate_image is set to true, height of the generated image. If the default value is used, the height is set to the value resulting from multiplying the aspect ratio by the width. The default value is ‘-1’.

  • search_radius – When interpolating the graph solution to generate the isochrone, neighborhood of influence of sample data (in percent of the image/grid). The default value is ‘20’.

  • grid_size – When interpolating the graph solution to generate the isochrone, number of subdivisions along the x axis when building the grid (the y is computed using the aspect ratio of the output image). The default value is ‘100’.

  • color_isolines – Color each isoline according to the colormap; otherwise, use the foreground color. Allowed values are:

    • true

    • false

    The default value is ‘true’.

  • add_labels – If set to true, add labels to the isolines. Allowed values are:

    • true

    • false

    The default value is ‘false’.

  • labels_font_size – When add_labels is set to true, size of the font (in pixels) to use for labels. The default value is ‘12’.

  • labels_font_family – When add_labels is set to true, font name to be used when adding labels. The default value is ‘arial’.

  • labels_search_window – When add_labels is set to true, a search window is used to rate the local quality of each isoline. Smooth, continuous, long stretches with relatively flat angles are favored. The provided value is multiplied by the labels_font_size to calculate the final window size. The default value is ‘4’.

  • labels_intralevel_separation – When add_labels is set to true, this value determines the distance (in multiples of the labels_font_size) to use when separating labels of different values. The default value is ‘4’.

  • labels_interlevel_separation – When add_labels is set to true, this value determines the distance (in percent of the total window size) to use when separating labels of the same value. The default value is ‘20’.

  • labels_max_angle – When add_labels is set to true, maximum angle (in degrees) from the vertical to use when adding labels. The default value is ‘60’.

The default value is an empty dict ( ).

options (dict of str to str) –

Additional parameters. Allowed keys are:

  • solve_table – Name of the table to host intermediate solve results, in [schema_name.]table_name format, using standard name resolution rules and meeting table naming criteria. This table will contain the position and cost for each vertex in the graph. If the default value is used, a temporary table is created and deleted once the solution is calculated. The default value is ‘’.

  • is_replicated – If set to true, replicate the solve_table. Allowed values are:

    • true

    • false

    The default value is ‘true’.

  • data_min_x – Lower bound for the x values. If not provided, it will be computed from the bounds of the input data.

  • data_max_x – Upper bound for the x values. If not provided, it will be computed from the bounds of the input data.

  • data_min_y – Lower bound for the y values. If not provided, it will be computed from the bounds of the input data.

  • data_max_y – Upper bound for the y values. If not provided, it will be computed from the bounds of the input data.

  • concavity_level – Factor to qualify the concavity of the isochrone curves. The lower the value, the more convex (with ‘0’ being completely convex and ‘1’ being the most concave). The default value is ‘0.5’. The minimum allowed value is ‘0’. The maximum allowed value is ‘1’.

  • use_priority_queue_solvers – Sets the solver methods explicitly if true. Allowed values are:

    • true – Uses the solvers scheduled for ‘shortest_path’ and ‘inverse_shortest_path’ based on solve_direction.

    • false – Uses the solvers ‘priority_queue’ and ‘inverse_priority_queue’ based on solve_direction.

    The default value is ‘false’.

  • solve_direction – Specify whether we are going to the source node, or starting from it. Allowed values are:

    • from_source – Shortest path to get to the source (inverse Dijkstra).

    • to_source – Shortest path to source (Dijkstra).

    The default value is ‘from_source’.

The default value is an empty dict ( ).

Returns

A dict with the following entries–

width (int) –

Width of the image as provided in width.

height (int) –

Height of the image as provided in height.

bg_color (long) –

Background color of the image as provided in bg_color.

image_data (bytes) –

Generated contour image data.

info (dict of str to str) –

Additional information.

solve_info (dict of str to str) –

Additional information.

contour_info (dict of str to str) –

Additional information.