Source code for climada.entity.exposures.litpop.gpw_population

This file is part of CLIMADA.

Copyright (C) 2017 ETH Zurich, CLIMADA contributors listed in AUTHORS.

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terms of the GNU General Public License as published by the Free
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Import data from Global Population of the World (GPW) datasets
import logging

import rasterio
import numpy as np

from climada.util.constants import SYSTEM_DIR
from climada import CONFIG

LOGGER = logging.getLogger(__name__)

[docs]def load_gpw_pop_shape(geometry, reference_year, gpw_version, data_dir=SYSTEM_DIR, layer=0, verbose=True): """Read gridded population data from TIFF and crop to given shape(s). Note: A (free) NASA Earthdata login is necessary to download the data. Data can be downloaded e.g. for gpw_version=11 and year 2015 from gpw-v4-population-count-rev11/ Parameters ---------- geometry : shape(s) to crop data to in degree lon/lat. for example shapely.geometry.(Multi)Polygon or shapefile.Shape from polygon(s) defined in a (country) shapefile. reference_year : int target year for data extraction gpw_version : int Version number of GPW population data, i.e. 11 for v4.11. The default is data_dir : Path, optional Path to data directory holding GPW data folders. The default is SYSTEM_DIR. layer : int, optional relevant data layer in input TIFF file to return. The default is 0 and should not be changed without understanding the different data layers in the given TIFF file. verbose : bool, optional Enable verbose logging about the used GPW version and reference year. Default: True. Returns ------- pop_data : 2D numpy array contains extracted population count data per grid point in shape first dimension is lat, second dimension is lon. meta : dict contains meta data per array, including "transform" with meta data on coordinates. global_transform : Affine instance contains six numbers, providing transform info for global GWP grid. global_transform is required for resampling on a globally consistent grid """ # check whether GPW input file exists and get file path file_path = get_gpw_file_path(gpw_version, reference_year, data_dir=data_dir, verbose=verbose) # open TIFF and extract cropped data from input file: with, 'r') as src: global_transform = src.transform pop_data, out_transform = rasterio.mask.mask(src, [geometry], crop=True, nodata=0) # extract and update meta data for cropped data and close src: meta = src.meta meta.update({ "driver": "GTiff", "height": pop_data.shape[1], "width": pop_data.shape[2], "transform": out_transform, }) return pop_data[layer,:,:], meta, global_transform
[docs]def get_gpw_file_path(gpw_version, reference_year, data_dir=None, verbose=True): """Check available GPW population data versions and year closest to `reference_year` and return full path to TIFF file. Parameters ---------- gpw_version : int (optional) Version number of GPW population data, i.e. 11 for v4.11. reference_year : int (optional) Data year is selected as close to reference_year as possible. The default is 2020. data_dir : pathlib.Path (optional) Absolute path where files are stored. Default: SYSTEM_DIR verbose : bool, optional Enable verbose logging about the used GPW version and reference year. Default: True. Raises ------ FileExistsError Returns ------- pathlib.Path : path to input file with population data """ if data_dir is None: data_dir = SYSTEM_DIR # get years available in GPW data from CONFIG and convert to array: years_available = np.array([ for year in CONFIG.exposures.litpop.gpw_population.years_available.list() ]) # find closest year to reference_year with data available: year = years_available[np.abs(years_available - reference_year).argmin()] if verbose and year != reference_year: LOGGER.warning('Reference year: %i. Using nearest available year for GPW data: %i', reference_year, year) # check if file is available for given GPW version, construct GPW file path from CONFIG: # if available, return full path to file: gpw_dirname = CONFIG.exposures.litpop.gpw_population.dirname_gpw.str() % (gpw_version, year) gpw_filename = CONFIG.exposures.litpop.gpw_population.filename_gpw.str() % (gpw_version, year) for file_path in [data_dir / gpw_filename, data_dir / gpw_dirname / gpw_filename]: if file_path.is_file(): if verbose:'GPW Version v4.%2i', gpw_version) return file_path # if the file was not found, an exception is raised with instructions on how to obtain it sedac_url = "" sedac_browse_url = f"{sedac_url}/data/collection/gpw-v4/sets/browse" sedac_file_url = ( f"{sedac_url}/downloads/data/gpw-v4/gpw-v4-population-count-rev{gpw_version}/" f"{gpw_dirname}.zip" ) raise FileNotFoundError( f'The file {file_path} could not be found. Please download the file first or choose a' f' different folder. The data can be downloaded from {sedac_browse_url}, e.g.,' f' {sedac_file_url} (Free NASA Earthdata login required).' )