What data format to use for plotting weather symbol with METAR data

[ccostanza10]

I'm pulling METAR data from LDM and opening the netCDF files. I'm using the presWeather variable.

I'd like to use something like this line to plot the weather symbols on a StationPlot.

stn_plot.plot_symbol('W',wx_symbol[mask],current_weather)

wx_symbol[mask] = ['' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '-SN' '-SN' '-SN BR' '' '' '-SN' '' '' '-SN BR' 'SN' '-SN' '-SN' '' '-SN BR' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '-SN' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '']

These would be strings, and I'm getting the following error, and the issue has something to do with the data type.

stn_plot.plot_symbol('W',wx_symbol[mask],current_weather)
File "/opt/local/anaconda3/lib/python3.7/site-packages/metpy/plots/station_plot.py", line 162, in plot_symbol
return self.plot_parameter(location, codes, symbol_mapper, **kwargs)
File "/opt/local/anaconda3/lib/python3.7/site-packages/metpy/plots/station_plot.py", line 204, in plot_parameter
text = self._to_string_list(parameter, formatter)
File "/opt/local/anaconda3/lib/python3.7/site-packages/metpy/plots/station_plot.py", line 380, in _to_string_list
return [formatter(v) if np.isfinite(v) else '' for v in vals]
File "/opt/local/anaconda3/lib/python3.7/site-packages/metpy/plots/station_plot.py", line 380, in
return [formatter(v) if np.isfinite(v) else '' for v in vals]
TypeError: ufunc 'isfinite' not supported for the input types, and the inputs could not be safely coerced to any supported types according to the casting rule ''safe''

Any thoughts on how to properly format the data to be used like stn_plot.plot_symbol('W',wx_symbol[mask],current_weather)?

[DanielAdriaansen]

Hi Carol,

It looks like the plot_symbol() function is expecting a numeric value that the WMO uses for various METAR weather types. You can see the table MetPy uses here:

MetPy/src/metpy/plots/wx_symbols.py

Lines 198 to 257 in 749cf07

	#####################################################################
	# This dictionary is for mapping METAR present weather text codes
	# to WMO codes for plotting wx symbols along with the station plots.
	# See Attachment IV of WMO No.306 for more information:
	# https://library.wmo.int/index.php?lvl=notice_display&id=13617
	# For unknown precipitation (UP), with thunderstorm this is mapped to 17, otherwise
	# it is mapped to 100 + automated station code
	wx_code_map = {'': 0, 'M': 0, 'TSNO': 0, 'VA': 4, 'FU': 4,
	'HZ': 5, 'DU': 6, 'BLDU': 1007, 'SA': 1007,
	'BLSA': 1007, 'VCBLSA': 1007, 'VCBLDU': 1007, 'BLPY': 1007,
	'PO': 8, 'VCPO': 8, 'VCDS': 9, 'VCSS': 9,
	'BR': 10, 'BCBR': 10, 'BC': 11, 'MIFG': 12,
	'VCTS': 13, 'VIRGA': 14, 'VCSH': 16, 'TS': 17,
	'THDR': 17, 'VCTSHZ': 17, 'TSFZFG': 17, 'TSBR': 17,
	'TSDZ': 17, 'VCTSUP': 17, '-TSUP': 17, 'TSUP': 17, '+TSUP': 17,
	'SQ': 18, 'FC': 19, '+FC': 19,
	'DS': 31, 'SS': 31, 'DRSA': 31, 'DRDU': 31,
	'+DS': 34, '+SS': 34, 'DRSN': 36, '+DRSN': 37,
	'-BLSN': 38, 'BLSN': 38, '+BLSN': 39, 'VCBLSN': 38,
	'VCFG': 40, 'BCFG': 41, 'PRFG': 44,
	'FG': 45, 'FZFG': 49, '-VCTSDZ': 51, '-DZ': 51,
	'-DZBR': 51, 'VCTSDZ': 53, 'DZ': 53, '+VCTSDZ': 55,
	'+DZ': 55, '-FZDZ': 56, '-FZDZSN': 56, 'FZDZ': 57,
	'+FZDZ': 57, 'FZDZSN': 57, '-DZRA': 58, 'DZRA': 59,
	'+DZRA': 59, '-RA': 61, '-RABR': 61, 'RA': 63, 'RABR': 63, 'RAFG': 63,
	'VCRA': 63, '+RA': 65, '-FZRA': 66, '-FZRASN': 66,
	'-FZRABR': 66, '-FZRAPL': 66, '-FZRASNPL': 66, 'TSFZRAPL': 67,
	'-TSFZRA': 67, 'FZRA': 67, '+FZRA': 67, 'FZRASN': 67,
	'TSFZRA': 67, '-DZSN': 68, '-RASN': 68, '-SNRA': 68,
	'-SNDZ': 68, 'RASN': 69, '+RASN': 69, 'SNRA': 69,
	'DZSN': 69, 'SNDZ': 69, '+DZSN': 69, '+SNDZ': 69,
	'-SN': 71, '-SNBR': 71, 'SN': 73, '+SN': 75,
	'-SNSG': 77, 'SG': 77, '-SG': 77, 'IC': 78,
	'-FZDZPL': 79, '-FZDZPLSN': 79, 'FZDZPL': 79, '-FZRAPLSN': 79,
	'FZRAPL': 79, '+FZRAPL': 79, '-RAPL': 79, '-RASNPL': 79,
	'-RAPLSN': 79, '+RAPL': 79, 'RAPL': 79, '-SNPL': 79,
	'SNPL': 79, '-PL': 79, 'PL': 79, '-PLSN': 79,
	'-PLRA': 79, 'PLRA': 79, '-PLDZ': 79, '+PL': 79,
	'PLSN': 79, 'PLUP': 79, '+PLSN': 79, '-SH': 80,
	'-SHRA': 80, 'SH': 81, 'SHRA': 81, '+SH': 81,
	'+SHRA': 81, '-SHRASN': 83, '-SHSNRA': 83, '+SHRABR': 84,
	'SHRASN': 84, '+SHRASN': 84, 'SHSNRA': 84, '+SHSNRA': 84,
	'-SHSN': 85, 'SHSN': 86, '+SHSN': 86, '-GS': 87,
	'-SHGS': 87, 'FZRAPLGS': 88, '-SNGS': 88, 'GSPLSN': 88,
	'GSPL': 88, 'PLGSSN': 88, 'GS': 88, 'SHGS': 88,
	'+GS': 88, '+SHGS': 88, '-GR': 89, '-SHGR': 89,
	'-SNGR': 90, 'GR': 90, 'SHGR': 90, '+GR': 90, '+SHGR': 90,
	'-TSRASN': 95, 'TSRASN': 95, '-TSSNRA': 95, 'TSSNRA': 95, '-VCTSRA': 1095,
	'-TSRA': 1095, 'TSRA': 1095, '-TSDZ': 1095, 'VCTSRA': 1095,
	'TSPL': 2095, '-TSSN': 2095, '-TSPL': 2095, 'TSSN': 2095, '-VCTSSN': 2095,
	'VCTSSN': 2095, 'TSPLSN': 2095, 'TSSNPL': 2095, '-TSSNPL': 2095,
	'-TSRAGR': 96, 'TSRAGS': 96, 'TSRAGR': 96, 'TSGS': 96, 'TSGR': 96,
	'+TSFZRAPL': 97, '+VCTSRA': 1097, '+TSRA': 1097, '+TSFZRA': 1097,
	'+TSSN': 2097, '+TSPL': 2097, '+TSPLSN': 2097, '+VCTSSN': 2097,
	'TSSA': 98, 'TSDS': 98, 'TSDU': 98,
	'+TSGS': 99, '+TSGR': 99, '+TSRAGS': 99, '+TSRAGR': 99,
	'IN': 141, '-UP': 141, 'UP': 141, '+UP': 142,
	'-FZUP': 147, 'FZUP': 147, '+FZUP': 148
	}

Maybe try converting your wx_symbol[mask] list to those numeric codes using: https://unidata.github.io/MetPy/latest/api/generated/metpy.plots.wx_code_to_numeric.html

Maybe something like:
stn_plot.plot_symbol('W',metpy.plots.wx_code_to_numeric(wx_symbol[mask]),current_weather)

I may not have the call to wx_code_to_numeric() exactly right depending on how you've imported MetPy so you might have to tinker with that a bit.

[ccostanza10]

Yes! Thanks @DanielAdriaansen that worked :)