satpy.utils module
Module defining various utilities.
- exception satpy.utils.PerformanceWarning[source]
Bases:
Warning
Warning raised when there is a possible performance impact.
- satpy.utils.atmospheric_path_length_correction(data, cos_zen, limit=88.0, max_sza=95.0)[source]
Perform Sun zenith angle correction.
This function uses the correction method proposed by Li and Shibata (2006): https://doi.org/10.1175/JAS3682.1
The correction is limited to
limit
degrees (default: 88.0 degrees). For larger zenith angles, the correction is the same as at thelimit
ifmax_sza
is None. The default behavior is to gradually reduce the correction pastlimit
degrees up tomax_sza
where the correction becomes 0. Bothdata
andcos_zen
should be 2D arrays of the same shape.
- satpy.utils.check_satpy(readers=None, writers=None, extras=None)[source]
Check the satpy readers and writers for correct installation.
- Parameters
- Returns: bool
True if all specified features were successfully loaded.
- satpy.utils.convert_remote_files_to_fsspec(filenames, storage_options=None)[source]
Check filenames for transfer protocols, convert to FSFile objects if possible.
- satpy.utils.debug(deprecation_warnings=True)[source]
Context manager to temporarily set debugging on.
Example:
>>> with satpy.utils.debug(): ... code_here()
- Parameters
deprecation_warnings (Optional[bool]) – Switch on deprecation warnings. Defaults to True.
- satpy.utils.debug_off()[source]
Turn debugging logging off.
This disables both debugging logging and the global visibility of deprecation warnings.
- satpy.utils.debug_on(deprecation_warnings=True)[source]
Turn debugging logging on.
Sets up a StreamHandler to to sys.stderr at debug level for all loggers, such that all debug messages (and log messages with higher severity) are logged to the standard error stream.
By default, since Satpy 0.26, this also enables the global visibility of deprecation warnings. This can be suppressed by passing a false value.
- Parameters
deprecation_warnings (Optional[bool]) – Switch on deprecation warnings. Defaults to True.
- Returns
None
- satpy.utils.find_in_ancillary(data, dataset)[source]
Find a dataset by name in the ancillary vars of another dataset.
- Parameters
data (xarray.DataArray) – Array for which to search the ancillary variables
dataset (str) – Name of ancillary variable to look for.
- satpy.utils.get_chunk_size_limit(dtype)[source]
Compute the chunk size limit in bytes given dtype.
- Returns
If PYTROLL_CHUNK_SIZE is not defined, this function returns None, otherwise it returns the computed chunk size in bytes.
- satpy.utils.get_satpos(data_arr: DataArray, preference: Optional[str] = None, use_tle: bool = False) tuple[float, float, float] [source]
Get satellite position from dataset attributes.
- Parameters
data_arr – DataArray object to access
.attrs
metadata from.preference –
Optional preference for one of the available types of position information. If not provided or
None
then the default preference is:Longitude & Latitude: nadir, actual, nominal, projection
Altitude: actual, nominal, projection
The provided
preference
can be any one of these individual strings (nadir, actual, nominal, projection). If the preference is not available then the original preference list is used. A warning is issued when projection values have to be used because nothing else is available and it wasn’t provided as thepreference
.use_tle – If true, try to obtain position via satellite name and TLE if it can’t be determined otherwise. This requires pyorbital, skyfield, and astropy to be installed and may need network access to obtain the TLE. Note that even if
use_tle
is true, the TLE will not be used if the dataset metadata contain the satellite position directly.
- Returns
Geodetic longitude, latitude, altitude [km]
- satpy.utils.get_storage_options_from_reader_kwargs(reader_kwargs)[source]
Read and clean storage options from reader_kwargs.
- satpy.utils.ignore_invalid_float_warnings()[source]
Ignore warnings generated for working with NaN/inf values.
Numpy and dask sometimes don’t like NaN or inf values in normal function calls. This context manager hides/ignores them inside its context.
Examples
Use around numpy operations that you expect to produce warnings:
with ignore_invalid_float_warnings(): np.nanmean(np.nan)
- satpy.utils.lonlat2xyz(lon, lat)[source]
Convert lon lat to cartesian.
For a sphere with unit radius, convert the spherical coordinates longitude and latitude to cartesian coordinates.
- Parameters
lon (number or array of numbers) – Longitude in °.
lat (number or array of numbers) – Latitude in °.
- Returns
(x, y, z) Cartesian coordinates [1]
- satpy.utils.proj_units_to_meters(proj_str)[source]
Convert projection units from kilometers to meters.
- satpy.utils.unify_chunks(*data_arrays: DataArray) tuple[xarray.core.dataarray.DataArray, ...] [source]
Run
xarray.unify_chunks()
if input dimensions are all the same size.This is mostly used in
satpy.composites.CompositeBase
to safe guard against runningdask.array.core.map_blocks()
with arrays of different chunk sizes. Doing so can cause unexpected results or errors. However, xarray’sunify_chunks
will raise an exception if dimensions of the provided DataArrays are different sizes. This is a common case for Satpy. For example, the “bands” dimension may be 1 (L), 2 (LA), 3 (RGB), or 4 (RGBA) for most compositor operations that combine other composites together.
- satpy.utils.xyz2lonlat(x, y, z, asin=False)[source]
Convert cartesian to lon lat.
For a sphere with unit radius, convert cartesian coordinates to spherical coordinates longitude and latitude.
- Parameters
x (number or array of numbers) – x-coordinate, unitless
y (number or array of numbers) – y-coordinate, unitless
z (number or array of numbers) – z-coordinate, unitless
asin (optional, bool) – If true, use arcsin for calculations. If false, use arctan2 for calculations.
- Returns
Longitude and latitude in °.
- Return type
(lon, lat)