opendrift.readers.basereader.variables

Module Contents

Classes

ReaderDomain	Projection, spatial and temporal domain of reader.
Variables	Handles reading and interpolation of variables.

Functions

land_binary_mask_from_ocean_depth(env)
wind_from_speed_and_direction(env, in_name, out_name)
vector_from_speed_and_direction(env, in_name, out_name)
reverse_direction(env, in_name, out_name)
magnitude_from_components(env, in_name, out_name)

Attributes

logger

opendrift.readers.basereader.variables.logger

class opendrift.readers.basereader.variables.ReaderDomain

Bases: opendrift.timer.Timeable

Projection, spatial and temporal domain of reader.

name

proj4

proj

lon

lat

xmin

xmax

ymin

ymax

zmin

zmax

delta_x

delta_y

shape

start_time

end_time

time_step

times

Setting this to True overrides temporal and spatial bounds checks. Also useful for readers that are constant and do not have a temporal dimension.

always_valid = False

center()

Returns center of reader (in lon, lat)

rotate_vectors(reader_x, reader_y, u_component, v_component, proj_from, proj_to)

Rotate vectors from one crs to another.

xy2lonlat(x, y)

Calculate x,y in own projection from given lon,lat (scalars/arrays).

lonlat2xy(lon, lat)

Calculate lon,lat from given x,y (scalars/arrays) in own projection.

y_azimuth(lon, lat)

Calculate azimuth orientation of the y-axis of the reader CRS.

pixel_size()

_coverage_unit_()

__repr__()

String representation of the current reader.

covers_positions_xy(x, y, z=0)

Return indices of input points covered by reader.

Arguments in native projection of reader.

modulate_longitude(lons)

Modulate the input longitude to the domain supported by the reader.

covers_positions(lon, lat, z=0)

Return indices of input points covered by reader.

global_coverage()

Return True if global coverage east-west

domain_grid(npoints=1000)

Return arrays of lon,lat points spread evenly over reader domain.

coverage_string()

Coverage of reader to be reported as string for debug output

check_arguments(variables, time, x, y, z)

Check validity of arguments input to method get_variables.

Checks that requested positions and time are within coverage of this reader, and that it can provide the requested variable(s). Returns the input arguments, possibly modified/corrected (below)

Arguments:

See function get_variables for definition.

Returns:

variables: same as input, but converted to list if given as string.

time: same as input, or start_time of reader if given as None.

x, y, z: same as input, but converted to ndarrays if given as scalars.

outside: boolean array which is True for any particles outside

the spatial domain covered by this reader.

Raises:

ValueError:

• if requested time is outside coverage of reader.

• if all requested positions are outside coverage of reader.

covers_time(time)

nearest_time(time)

Return nearest times before and after the requested time.

Returns:

nearest_time: datetime time_before: datetime time_after: datetime indx_nearest: int indx_before: int indx_after: int

opendrift.readers.basereader.variables.land_binary_mask_from_ocean_depth(env)

opendrift.readers.basereader.variables.wind_from_speed_and_direction(env, in_name, out_name)

opendrift.readers.basereader.variables.vector_from_speed_and_direction(env, in_name, out_name)

opendrift.readers.basereader.variables.reverse_direction(env, in_name, out_name)

opendrift.readers.basereader.variables.magnitude_from_components(env, in_name, out_name)

class opendrift.readers.basereader.variables.Variables

Bases: ReaderDomain

Handles reading and interpolation of variables.

variables

derived_variables

name

buffer = 0

activate_environment_mapping(mapping_name)

__calculate_derived_environment_variables__(env)

set_buffer_size(max_speed, time_coverage=None)

Adjust buffer to minimise data block size needed to cover elements.

The buffer size is calculated from the maximum anticpated speed. Seeding over a large area or over longer time can easily cause particles to be located outside the block. This is not critical, but causes interpolation to be one-sided in time for the relevant particles.

Args:

max_speed (m/s): the maximum speed anticipated for particles. time_coverage (timedelta): the time span to cover

__check_env_coordinates__(env)

Make sure x and y are floats (and not e.g. int64)

static __check_variable_array__(name, variable)

Ensure arrays are not masked arrays and that values are within valid ranges.

__check_env_arrays__(env)

Ensure arrays are not masked arrays and that values are within valid ranges.

See also

Disabled in StructuredReader because variables are valided before entered into interpolator:

structured.StructuredReader.__check_env_arrays__()

abstract _get_variables_interpolated_(variables, profiles, profiles_depth, time, reader_x, reader_y, z)

This method _must_ be implemented by every reader. Usually by subclassing one of the reader types (e.g. structured.StructuredReader).

Arguments are in _native projection_ of reader.

get_variables_interpolated_xy(variables, profiles=None, profiles_depth=None, time=None, x=None, y=None, z=None, rotate_to_proj=None)

Get variables in native projection of reader.

See also

• get_variables_interpolated().

• _get_variables_interpolated_().

get_variables_interpolated(variables, profiles=None, profiles_depth=None, time=None, lon=None, lat=None, z=None, rotate_to_proj=None)

get_variables_interpolated is the main interface to opendrift.basemodel.OpenDriftSimulation, and is responsible for returning variables at the correct positions.

Readers should implement _get_variables_interpolated_().

Arguments:

variables: string, or list of strings (standard_name) of

requested variables. These must be provided by reader.

profiles: List of variable names that should be returned for the range in profiles_depth.

profiles_depth: A range [z-start, z-end] for which to return values for profile-variables. The exact z-depth are given by the reader and returned as z variable in env_profiles.

time: datetime or None, time at which data are requested.

Can be None (default) if reader/variable has no time dimension (e.g. climatology or landmask).

lon: longitude, 1d array.

lat: latitude, 1d array, same length as lon.

z: float or ndarray; vertical position (in meters, positive up)

of requested points. either scalar or same length as lon, lat. default: 0 m (unless otherwise documented by reader)

block: bool, see return below

rotate_to_proj: N/A

Returns:

(env, env_profiles)

Interpolated variables at x, y and z. env contains values at a fixed depth (z), while env_profiles contains depth-profiles in the range profile_depth for the variables listed in profiles for each element (in x, y). The exact depth is determined by the reader and specified in env_profiles[‘z’]. Thus variables in env_profiles are not interpolated in z-direction.

See also

get_variables_interpolated_xy().