##############################################################
# ENVI header file management
# John Truckenbrodt 2015-2026
##############################################################
"""
This module offers functionality for editing ENVI header files
"""
from __future__ import annotations
import re
import zipfile as zf
from types import TracebackType
from typing import Any
from .ancillary import parse_literal
[docs]
def hdr(data: str | dict[str, Any] | HDRobject, filename: str) -> None:
"""
write ENVI header files
Parameters
----------
data
the file or dictionary to get the info from
filename
the HDR file to write
"""
hdrobj = data if isinstance(data, HDRobject) else HDRobject(data)
hdrobj.write(filename)
[docs]
class HDRobject:
"""
ENVI HDR info handler
Parameters
----------
The file or dictionary to get the info from. If None (default), an
object with default values for an empty raster file is returned.
Examples
--------
>>> from spatialist.envi import HDRobject
>>> with HDRobject('E:/test.hdr') as hdr:
>>> hdr.band_names = ['one', 'two']
>>> print(hdr)
>>> hdr.write()
"""
filename: str | None
def __init__(self, data: str | dict[str, Any] | None = None):
self.filename = data if isinstance(data, str) else None
if isinstance(data, str):
if re.search('.hdr$', data):
args = self.__hdr2dict()
else:
raise RuntimeError('the data does not seem to be a ENVI HDR file')
elif data is None:
args = {'bands': 1,
'header_offset': 0,
'file_type': 'ENVI Standard',
'interleave': 'bsq',
'sensor_type': 'Unknown',
'byte_order': 0,
'wavelength_units': 'Unknown',
'samples': 0,
'lines': 0}
elif isinstance(data, dict):
args = data
else:
raise RuntimeError('parameter data must be of type str, dict or None')
for arg in args:
setattr(self, arg, args[arg])
def __enter__(self) -> HDRobject:
return self
def __exit__(
self,
exc_type: type[BaseException] | None,
exc_val: BaseException | None,
exc_tb: TracebackType | None
) -> None:
return None
def __str__(self) -> str:
lines = ['ENVI']
for item in ['description', 'acquisition_time', 'samples', 'lines', 'bands', 'header_offset', 'file_type',
'data_type', 'data_ignore_value', 'interleave', 'sensor_type', 'byte_order', 'map_info',
'coordinate_system_string', 'wavelength_units', 'band_names']:
if hasattr(self, item):
value = getattr(self, item)
if isinstance(value, (list, map)):
lines.append(item.replace('_', ' ') + ' = {' + ', '.join([str(x) for x in value]) + '}')
elif item in ['description', 'band_names', 'coordinate_system_string']:
lines.append(item.replace('_', ' ') + ' = {' + str(value) + '}')
else:
lines.append(item.replace('_', ' ') + ' = ' + str(value) + '')
return '\n'.join(lines)
def __hdr2dict(self) -> dict[str, Any]:
"""
Read a HDR file into a dictionary.
https://gis.stackexchange.com/questions/48618/how-to-read-write-envi-metadata-using-gdal
Returns
-------
the hdr file metadata attributes
"""
if '.zip' in self.filename:
match = re.search('.zip', self.filename)
zip = self.filename[:match.end()]
with zf.ZipFile(zip, 'r') as zip:
member = self.filename[match.end():].strip('\\/')
content = zip.read(member)
lines = content.decode().split('\n')
else:
with open(self.filename, 'r') as infile:
lines = infile.readlines()
i = 0
out = dict()
while i < len(lines):
line = lines[i].strip('\r\n')
if '=' in line:
if '{' in line and '}' not in line:
while '}' not in line:
i += 1
line += lines[i].strip('\n').lstrip()
line = list(filter(None, re.split(r'\s+=\s+', line)))
line[1] = re.split(',[ ]*', line[1].strip('{}'))
key = line[0].replace(' ', '_')
val = line[1] if len(line[1]) > 1 else line[1][0]
out[key] = parse_literal(val)
i += 1
if 'band_names' in out.keys() and not isinstance(out['band_names'], list):
out['band_names'] = [out['band_names']]
return out
[docs]
def write(self, filename: str = 'same') -> None:
"""
write object to an ENVI header file
"""
if filename == 'same':
filename = self.filename
if not filename.endswith('.hdr'):
filename += '.hdr'
with open(filename, 'w') as out:
out.write(self.__str__())