simplify type="hollow"

finish simplify `type="hollow"

wick also should match up/down color for type=`hollow`

Author: DanielGoldfarb

examples/hollow_candles.ipynb

@@ -1,10 +1,10 @@
 style = dict(style_name    = 'hollow',
              base_mpl_style= 'seaborn-darkgrid', 
-             marketcolors  = {'candle' : {'up':(0,0,0,0), 'down':'r'},
-                              'hollow' : {'up':'k', 'down':(0,0,0,0)},
+             marketcolors  = {'candle'  : {'up':'k', 'down':'r'},
                               'edge'    : {'up':'k', 'down':'r'},
                               'wick'    : {'up':'k', 'down':'r'},
                               'ohlc'    : {'up':'k', 'down':'r'},
+                              'hollow'  : 'w',
                               'volume'  : {'up':'#1f77b4', 'down':'#1f77b4'},
                               'vcedge'  : {'up':'#1f77b4', 'down':'#1f77b4'},
                               'vcdopcod': False, # Volume Color is Per Price Change On Day

src/mplfinance/_styledata/hollow.py

@@ -94,6 +94,9 @@ def _valid_make_mpf_style_kwargs():
         'rc'            : { 'Default'     : None,
                             'Validator'   : lambda value: isinstance(value,dict) },
 
+        'style_name'    : { 'Default'     : None,
+                            'Validator'   : lambda value: isinstance(value,str) },
+
     }
     _validate_vkwargs_dict(vkwargs)
     return vkwargs
@@ -160,7 +163,10 @@ def _valid_make_marketcolors_kwargs():
         'down'       : { 'Default'     : None,
                          'Validator'   : lambda value: mcolors.is_color_like(value) },
 
-        'alpha'       : { 'Default'     : None,
+        'hollow'     : { 'Default'     : None,
+                         'Validator'   : lambda value: mcolors.is_color_like(value) },
+
+        'alpha'      : { 'Default'     : None,
                          'Validator'   : lambda value: ( isinstance(value,float) and
                                                          0.0 <= value and 1.0 >= value ) },
 
@@ -230,7 +236,6 @@ def make_marketcolors(**kwargs):
         candle.update(down=down)
         marketcolors.update(down=down)
 
-
     def _check_and_set_mktcolor(candle,**kwarg):
         if len(kwarg) != 1:
             raise ValueError('Expect only ONE kwarg')
@@ -259,6 +264,9 @@ def _check_and_set_mktcolor(candle,**kwarg):
             c   = _check_and_set_mktcolor(candle,**kwa)
             marketcolors.update([(kw,c)])
 
+    if config['hollow'] is not None:
+        marketcolors.update({'hollow':config['hollow']})
+
     if config['alpha'] is not None:
         marketcolors.update({'alpha':config['alpha']})
 

src/mplfinance/_styles.py

@@ -165,13 +165,13 @@ def _updown_colors(upcolor,downcolor,opens,closes,use_prev_close=False):
         return [first] + _list
 
 
-def _updownhollow_colors(upcolor,downcolor,uphollow,downhollow,opens,closes):
-    if upcolor == downcolor == downhollow== uphollow:
+def _updownhollow_colors(upcolor,downcolor,hollowcolor,opens,closes):
+    if upcolor == downcolor:
         return upcolor
-    umap = {True : upcolor, False : uphollow}
-    dmap = {True : downcolor, False : downhollow}
-    _list = [umap[cls > opn] if cls > cls0 else dmap[cls < opn] for opn0,cls0,opn,cls in zip(opens[0:-1],closes[0:-1],opens[1:],closes[1:]) ]
-    first = upcolor if closes[0] > opens[0] else downcolor
+    umap = {True : hollowcolor, False : upcolor  }
+    dmap = {True : hollowcolor, False : downcolor}
+    first = umap[closes[0] > opens[0]]
+    _list = [ umap[cls > opn] if cls > cls0 else dmap[cls > opn] for opn0,cls0,opn,cls in zip(opens[0:-1],closes[0:-1],opens[1:],closes[1:]) ]
     return [first] + _list
 
 
@@ -488,17 +488,6 @@ def _construct_candlestick_collections(dates, opens, highs, lows, closes, market
     return [rangeCollection, barCollection]
 
 
-def alpha_handler(color, alpha):
-    """Checks the color input for an alpha value. Returns the rgba color code with lesser
-    of existing or provided alpha
-    """
-    color_code = mcolors.to_rgba(color)
-    if color_code[-1] <= alpha:
-        return color_code
-    else:
-        return  mcolors.to_rgba(color, alpha)
-
-
 def _construct_hollow_candlestick_collections(dates, opens, highs, lows, closes, marketcolors=None, config=None):
     """Represent the open, close as a bar line and high low range as a
     vertical line. Same as basic candlestick, but utilizes solid and hollow candlesticks
@@ -530,7 +519,7 @@ def _construct_hollow_candlestick_collections(dates, opens, highs, lows, closes,
     _check_input(opens, highs, lows, closes)
 
     if marketcolors is None:
-        marketcolors = _get_mpfstyle('hollow')['marketcolors']
+        marketcolors = _get_mpfstyle('classic')['marketcolors']
         #print('default market colors:',marketcolors)
 
     datalen = len(dates)
@@ -555,22 +544,16 @@ def _construct_hollow_candlestick_collections(dates, opens, highs, lows, closes,
 
     alpha  = marketcolors['alpha']
 
-    uc     = alpha_handler(marketcolors['candle'][ 'up' ], alpha)
-    dc     = alpha_handler(marketcolors['candle']['down'], alpha)
-    try:
-        uh     = alpha_handler(marketcolors['hollow']['up'], alpha)
-        dh     = alpha_handler(marketcolors['hollow']['down'], alpha)
-    except KeyError as e:
-        raise Exception('Improper style definition for hollow candle type plotting') from e
-    colors = _updownhollow_colors(uc, dc, uh, dh, opens, closes)
+    uc     = mcolors.to_rgba(marketcolors['candle'][ 'up' ], alpha)
+    dc     = mcolors.to_rgba(marketcolors['candle']['down'], alpha)
+   
+    hc = mcolors.to_rgba(marketcolors['hollow']) if 'hollow' in marketcolors else (0,0,0,0)
+    
+    colors = _updownhollow_colors(uc, dc, hc, opens, closes)  # for candle body.
 
-    uc     = mcolors.to_rgba(marketcolors['edge'][ 'up' ], 1.0)
-    dc     = mcolors.to_rgba(marketcolors['edge']['down'], 1.0)
-    edgecolor = _updownhollow_colors(uc, dc, uc, dc, opens, closes)
+    edgecolor = _updown_colors(uc, dc, opens, closes, use_prev_close=True)
 
-    uc     = mcolors.to_rgba(marketcolors['wick'][ 'up' ], 1.0)
-    dc     = mcolors.to_rgba(marketcolors['wick']['down'], 1.0)
-    wickcolor = _updownhollow_colors(uc, dc, uc, dc, opens, closes)
+    wickcolor = _updown_colors(uc, dc, opens, closes, use_prev_close=True)
 
     lw = config['_width_config']['candle_linewidth']