SHP.merge_layers¶

classmethod SHP.merge_layers(shp_zip_pathnames, layer_name, engine='geopandas', rm_zip_extracts=True, output_dir=None, rm_shp_temp=True, ret_shp_pathname=False, verbose=False, raise_error=False)[source]¶

Merge shapefiles over a layer for multiple geographic regions.

Parameters:

shp_zip_pathnames (list) – list of paths to data of shapefiles (in .shp.zip format)
layer_name (str) – name of a layer (e.g. ‘railways’)
engine (str) – the open-source package used to merge/save shapefiles; options include: 'pyshp' and 'geopandas' (default) (or 'gpd') if engine='geopandas', this function relies on geopandas.GeoDataFrame.to_file(); otherwise, it by default uses shapefile.Writer()
rm_zip_extracts (bool) – whether to delete the extracted files, defaults to False
rm_shp_temp (bool) – whether to delete temporary layer files, defaults to False
output_dir (str | None) – if None (default), use the layer name as the name of the folder where the merged .shp files will be saved
ret_shp_pathname (bool) – whether to return the pathname of the merged .shp file, defaults to False
verbose (bool | int) – whether to print relevant information in console, defaults to False
raise_error (bool) – Whether to raise the provided exception; if raise_error=False (default), the error will be suppressed.

Returns:

the path to the merged file when ret_merged_shp_path=True

Return type:

list

Note

This function does not create projection (.prj) for the merged map. See also [MMS-1].
For valid layer_name, check the function valid_shapefile_layer_names().

Examples:

>>> # To merge 'railways' layers of Greater Manchester and West Yorkshire"

>>> from pydriosm.reader._shp import SHP
>>> from pydriosm.downloader import BBBikeDownloader
>>> from pyhelpers.dirs import delete_dir
>>> import os

>>> # Download the .shp.zip file of Manchester and West Yorkshire
>>> subrgn_names = ['London', 'Birmingham']
>>> file_fmt = ".shp"
>>> data_dir = "tests/osm_data"

>>> bbd = BBBikeDownloader()

>>> bbd.download_data(subrgn_names, file_fmt, data_dir, verbose=True)
Proceed to download data in the format '.shp.zip' for the following geographic (sub...
    "London"
    "Birmingham"
  to "./tests/osm_data/"
? [No]|Yes: yes
Downloading "London.osm.shp.zip" 100%|██████████| 248M/248M | 18.1MB/s | ETA:...
  Saving "London.osm.shp.zip" to "./tests/osm_data/london/" ... Done.
Downloading "Birmingham.osm.shp.zip" 100%|██████████| 79.1M/79.1M | 16.0MB/s ...
  Saving "Birmingham.osm.shp.zip" to "./tests/osm_data/birmingham/" ... Done.

>>> os.path.relpath(bbd.download_dir)
'tests\osm_data'
>>> len(bbd.data_paths)
2

>>> # Merge the layers of 'railways' of the two subregions
>>> merged_shp_path = SHP.merge_shp_layers(
...     bbd.data_paths, layer_name='railways', verbose=True, ret_shp_pathname=True)
Merging the following shapefiles:
  "london_railways.shp"
  "birmingham_railways.shp"
  In progress ... Done.
    Find the merged shapefile in "./tests/osm_data/lon-bir-railways/".

>>> # Check the pathname of the merged shapefile
>>> type(merged_shp_path)
list
>>> len(merged_shp_path)
1
>>> os.path.relpath(merged_shp_path[0])
'tests\osm_data\lon-bir-railways\lon-bir-railways.shp'

>>> # Read the merged .shp file
>>> merged_shp_data = SHP.read_shp(merged_shp_path[0])
>>> merged_shp_data.head()
   osm_id  ...                                           geometry
0   30804  ...     LINESTRING (0.00486 51.62793, 0.0062 51.62927)
1  101298  ...  LINESTRING (-0.22499 51.4937, -0.22516 51.4945...
2  101486  ...  LINESTRING (-0.20555 51.51954, -0.20514 51.519...
3  101511  ...  LINESTRING (-0.2119 51.52419, -0.21081 51.5239...
4  282898  ...   LINESTRING (-0.1862 51.61592, -0.18687 51.61386)
[5 rows x 4 columns]

>>> # Delete the test data directory
>>> delete_dir(bbd.download_dir, verbose=True)
To delete the directory "./tests/osm_data/" (Not empty)
? [No]|Yes: yes
Deleting "./tests/osm_data/" ... Done.