sam iotools pvlib#1371

adds a sam.py, and pytest

Author: shirubana

pvlib/iotools/__init__.py

@@ -21,3 +21,4 @@
 from pvlib.iotools.sodapro import get_cams  # noqa: F401
 from pvlib.iotools.sodapro import read_cams  # noqa: F401
 from pvlib.iotools.sodapro import parse_cams  # noqa: F401
+from pvlib.iotools.sam import saveSAM_WeatherFile, tz_convert  # noqa: F401

pvlib/iotools/sam.py

@@ -0,0 +1,164 @@
+"""Functions for reading and writing SAM data files."""
+
+import pandas as pd
+
+def saveSAM_WeatherFile(data, metadata, savefile='SAM_WeatherFile.csv', standardSAM = True, includeminute=False):
+    """
+    Saves a dataframe with weather data from pvlib format on SAM-friendly format.
+
+    Parameters
+    -----------
+    data : pandas.DataFrame
+        timeseries data in PVLib format. Should be TZ converted (not UTC). Ideally it is one sequential year data; if not suggested to use standardSAM = False. 
+    metdata : dictionary
+        Dictionary with at least 'latitude', 'longitude', 'elevation', 'source', and 'TZ' for timezone.
+    savefile : str
+        Name of file to save output as. 
+    standardSAM : boolean
+        This checks the dataframe to avoid having a leap day, then averages it to SAM style (closed to the right), 
+        and fills the years so it starst on YEAR/1/1 0:0 and ends on YEAR/12/31 23:00.
+    includeminute ; Bool
+        For hourly data, if SAM input does not have Minutes, it calculates the sun position 30 minutes 
+        prior to the hour (i.e. 12 timestamp means sun position at 11:30)
+        If minutes are included, it will calculate the sun position at the time of the timestamp (12:00 at 12:00)
+        Set to true if resolution of data is sub-hourly.
+
+    Returns
+    -------
+    Nothing, it just writes the file.
+    
+    """
+
+    def _is_leap_and_29Feb(s):
+        ''' Creates a mask to help remove Leap Years. Obtained from: 
+            https://stackoverflow.com/questions/34966422/remove-leap-year-day-from-pandas-dataframe/34966636
+        '''
+        return (s.index.year % 4 == 0) & \
+               ((s.index.year % 100 != 0) | (s.index.year % 400 == 0)) & \
+               (s.index.month == 2) & (s.index.day == 29)
+
+    def _averageSAMStyle(df, interval='60T', closed='right', label='right'):
+        ''' Averages subhourly data into hourly data in SAM's expected format. 
+        '''
+        try:
+            df = df.resample(interval, closed=closed, label=label).mean() #
+        except:
+            print('Warning - unable to average')
+        return df
+
+    def _fillYearSAMStyle(df, freq='60T'):
+        ''' Fills year 
+        '''
+        # add zeros for the rest of the year
+        if freq is None:
+            try:
+                freq = pd.infer_freq(df.index)
+            except:
+                freq = '60T'  # 15 minute data by default
+        # add a timepoint at the end of the year
+        # idx = df.index
+        # apply correct TZ info (if applicable)
+        tzinfo = df.index.tzinfo
+        starttime = pd.to_datetime('%s-%s-%s %s:%s' % (df.index.year[0],1,1,0,0 ) ).tz_localize(tzinfo)
+        endtime = pd.to_datetime('%s-%s-%s %s:%s' % (df.index.year[-1],12,31,23,60-int(freq[:-1])) ).tz_localize(tzinfo)
+
+        df2 = _averageSAMStyle(df, freq)
+        df2.iloc[0] = 0  # set first datapt to zero to forward fill w zeros
+        df2.iloc[-1] = 0  # set last datapt to zero to forward fill w zeros
+        df2.loc[starttime] = 0
+        df2.loc[endtime] = 0
+        df2 = df2.resample(freq).ffill() 
+        return df2
+
+    
+    # Modify this to cut into different years. Right now handles partial year and sub-hourly interval.
+    if standardSAM:
+        filterdatesLeapYear = ~(_is_leap_and_29Feb(data)) 
+        data = data[filterdatesLeapYear]
+        data = _fillYearSAMStyle(data)
+
+
+    # metadata
+    latitude=metadata['latitude']
+    longitude=metadata['longitude']
+    elevation=metadata['elevation']
+    timezone_offset = metadata['TZ']
+    source = metadata['source']
+    
+    # make a header        
+    header = '\n'.join(
+            [ 'Source,Latitude,Longitude,Time Zone,Elevation',
+            source + ',' + str(latitude) + ',' + str(longitude) + ',' + str(timezone_offset) + ',' + str(elevation)]) + '\n'
+
+    savedata = pd.DataFrame({'Year':data.index.year, 'Month':data.index.month, 'Day':data.index.day,
+                             'Hour':data.index.hour})
+
+    if includeminute:
+        savedata['Minute'] = data.index.minute
+
+    windspeed = list(data.wind_speed)
+    temp_amb = list(data.temp_air)
+    savedata['Wspd'] = windspeed
+    savedata['Tdry'] = temp_amb
+    
+    if 'dni' in data:
+        dni = list(data.dni)
+        savedata['DHI'] = dni
+    
+    if 'dhi' in data:
+        dhi = list(data.dhi)
+        savedata['DNI'] = dhi
+                            
+    if 'ghi' in data:
+        ghi = list(data.ghi)
+        savedata['GHI'] = ghi
+    
+    if 'poa' in data: # This is a nifty function of SAM for using field measured POA irradiance!
+        poa = list(data.poa)
+        savedata['POA'] = poa
+        
+    if 'albedo' in data: 
+        albedo = list(data.albedo)
+        savedata['Albedo'] = albedo
+
+    with open(savefile, 'w', newline='') as ict:
+        # Write the header lines, including the index variable for
+        # the last one if you're letting Pandas produce that for you.
+        # (see above).
+        for line in header:
+            ict.write(line)
+
+        savedata.to_csv(ict, index=False)
+
+
+def tz_convert(df, tz_convert_val, metadata=None):
+    """
+    Support function to convert metdata to a different local timezone. Particularly for 
+    GIS weather files which are returned in UTC by default.
+    
+    Parameters
+    ----------
+    df : DataFrame
+        A dataframe in UTC timezone
+    tz_convert_val : int
+        Convert timezone to this fixed value, following ISO standard 
+        (negative values indicating West of UTC.)
+    Returns: metdata, metadata  
+    
+
+    Returns
+    -------
+    df : DataFrame
+        Dataframe in the converted local timezone.
+    metadata : dict
+        Adds (or updates) the existing Timezone in the metadata dictionary
+
+    """
+    import pytz
+    if (type(tz_convert_val) == int) | (type(tz_convert_val) == float):
+        df = df.tz_convert(pytz.FixedOffset(tz_convert_val*60))
+
+        if metadata is not None:
+            metadata['TZ'] = tz_convert_val
+            return df, metadata
+    return df

pvlib/tests/iotools/test_sam.py

@@ -0,0 +1,29 @@
+"""
+test the SAM IO tools
+"""
+import pandas as pd
+from pvlib.iotools import get_pvgis_tmy, read_pvgis_hourly
+from pvlib.iotools import saveSAM_WeatherFile, tz_convert
+from ..conftest import (DATA_DIR, RERUNS, RERUNS_DELAY, assert_frame_equal,
+                        fail_on_pvlib_version)
+
+# PVGIS Hourly tests
+# The test files are actual files from PVGIS where the data section have been
+# reduced to only a few lines
+testfile_radiation_csv = DATA_DIR / \
+    'pvgis_hourly_Timeseries_45.000_8.000_SA_30deg_0deg_2016_2016.csv'
+
+# REMOVE
+testfile_radiation_csv = r'C:\Users\sayala\Documents\GitHub\pvlib-python\pvlib\data\pvgis_hourly_Timeseries_45.000_8.000_SA_30deg_0deg_2016_2016.csv'
+
+def test_saveSAM_WeatherFile():
+    data, inputs, metadata = read_pvgis_hourly(testfile_radiation_csv, map_variables=True)#, pvgis_format=pvgis_format)
+    metadata = {'latitude': inputs['latitude'],
+           'longitude': inputs['longitude'],
+           'elevation': inputs['elevation'],
+           'source': 'User-generated'}
+    metadata['TZ'] = -7        
+    data = tz_convert(data, tz_convert_val=metadata['TZ'])
+    coerce_year=2021  # read_pvgis_hourly does not coerce_year, so doing it here.
+    data.index = data.index.map(lambda dt: dt.replace(year=coerce_year))
+    saveSAM_WeatherFile(data, metadata, savefile='test_SAMWeatherFile.csv', standardSAM=True)