How to use the pyproj.CRS.from_string function in pyproj

def test_is_same_crs():
    crs1 = CRS("urn:ogc:def:crs:OGC::CRS84")
    crs2 = CRS("EPSG:3857")

    assert crs1 == crs1
    assert crs1 != crs2

    wgs84_crs = CRS.from_string("+proj=longlat +ellps=WGS84 +datum=WGS84")
    assert crs1 == wgs84_crs

    # Make sure that same projection with different parameter are not equal
    lcc_crs1 = CRS.from_string(
        "+lon_0=-95 +ellps=GRS80 +y_0=0 +no_defs=True +proj=lcc "
        "+x_0=0 +units=m +lat_2=77 +lat_1=49 +lat_0=0"
    )
    lcc_crs2 = CRS.from_string(
        "+lon_0=-95 +ellps=GRS80 +y_0=0 +no_defs=True +proj=lcc "
        "+x_0=0 +units=m +lat_2=77 +lat_1=45 +lat_0=0"
    )
    assert lcc_crs1 != lcc_crs2

def test_is_projected():
    assert CRS("EPSG:3857").is_projected is True

    lcc_crs = CRS.from_string(
        "+lon_0=-95 +ellps=GRS80 +y_0=0 +no_defs=True +proj=lcc +x_0=0 "
        "+units=m +lat_2=77 +lat_1=49 +lat_0=0"
    )
    assert CRS.from_user_input(lcc_crs).is_projected is True

    wgs84_crs = CRS.from_string("+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs")
    assert CRS.from_user_input(wgs84_crs).is_projected is False

def test_from_epsg_string():
    proj = CRS.from_string("epsg:4326")
    assert proj.to_epsg() == 4326

    # Test with invalid EPSG code
    with pytest.raises(CRSError):
        assert CRS.from_string("epsg:xyz")

def test_is_projected():
    assert CRS("EPSG:3857").is_projected is True

    lcc_crs = CRS.from_string(
        "+lon_0=-95 +ellps=GRS80 +y_0=0 +no_defs=True +proj=lcc +x_0=0 "
        "+units=m +lat_2=77 +lat_1=49 +lat_0=0"
    )
    assert CRS.from_user_input(lcc_crs).is_projected is True

    wgs84_crs = CRS.from_string("+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs")
    assert CRS.from_user_input(wgs84_crs).is_projected is False

def test_epsg__not_found():
    assert CRS("+proj=longlat +datum=WGS84 +no_defs +towgs84=0,0,0").to_epsg(0) is None
    assert (
        CRS.from_string("+proj=longlat +datum=WGS84 +no_defs +towgs84=0,0,0").to_epsg()
        is None
    )

def test_from_proj4_json():
    json_str = '{"proj": "longlat", "ellps": "WGS84", "datum": "WGS84"}'
    proj = CRS.from_string(json_str)
    with pytest.warns(UserWarning):
        assert proj.to_proj4(4) == "+proj=longlat +datum=WGS84 +no_defs +type=crs"
        assert proj.to_proj4(5) == "+proj=longlat +datum=WGS84 +no_defs +type=crs"
    # Test with invalid JSON code
    with pytest.raises(CRSError):
        assert CRS.from_string("{foo: bar}")

def test_from_string():
    wgs84_crs = CRS.from_string("+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs")
    with pytest.warns(UserWarning):
        assert wgs84_crs.to_proj4() == "+proj=longlat +datum=WGS84 +no_defs +type=crs"
    # Make sure this doesn't get handled using the from_epsg()
    # even though 'epsg' is in the string
    with pytest.warns(FutureWarning):
        epsg_init_crs = CRS.from_string("+init=epsg:26911 +units=m +no_defs=True")
    with pytest.warns(UserWarning):
        assert (
            epsg_init_crs.to_proj4()
            == "+proj=utm +zone=11 +datum=NAD83 +units=m +no_defs +type=crs"
        )

def test_crs_OSR_equivalence():
    crs1 = CRS.from_string("+proj=longlat +datum=WGS84 +no_defs")
    crs2 = CRS.from_string("+proj=latlong +datum=WGS84 +no_defs")
    with pytest.warns(FutureWarning):
        crs3 = CRS({"init": "EPSG:4326"})
    assert crs1 == crs2
    # these are not equivalent in proj.4 now as one uses degrees and the othe radians
    assert crs1 == crs3

def test_crs_OSR_equivalence():
    crs1 = CRS.from_string("+proj=longlat +datum=WGS84 +no_defs")
    crs2 = CRS.from_string("+proj=latlong +datum=WGS84 +no_defs")
    with pytest.warns(FutureWarning):
        crs3 = CRS({"init": "EPSG:4326"})
    assert crs1 == crs2
    # these are not equivalent in proj.4 now as one uses degrees and the othe radians
    assert crs1 == crs3

grid_mapping_variable = nc_handle[variable].grid_mapping
    elif hasattr(nc_handle[variable], 'grid_mapping_name') and \
            nc_handle[variable].grid_mapping_name in _valid_cf_type_of_grid_mapping:
        # this looks like a valid grid_mapping variable
        try:
            # try to load it
            crs = _load_crs_from_cf_gridmapping(nc_handle, variable)
            grid_mapping_variable = variable
            variable_is_itself_gridmapping = True
        except pyproj.exceptions.CRSError as ex:
            raise ValueError("ERROR: pyproj didn't manage to load the CRS: {}".format(ex))
    else:
        # fallback position: maybe the variable is on a basic lat/lon grid with no
        #   grid_mapping. Note: there is no default CRS in CF, we choose WGS84
        grid_mapping_variable = "latlon_default"
        crs = pyproj.CRS.from_string('+proj=latlon +datum=WGS84 +ellps=WGS84')

    # return
    return crs, grid_mapping_variable, variable_is_itself_gridmapping