Merge pull request #369 from pankaj3009/master

Feature Request: Ability to plot step /staircase lines implemented Is…

Author: DanielGoldfarb

src/mplfinance/_version.py

@@ -1,5 +1,5 @@
 
-version_info = (0, 12, 7, 'alpha', 15)
+version_info = (0, 12, 7, 'alpha', 16)
 
 _specifier_ = {'alpha': 'a','beta': 'b','candidate': 'rc','final': ''}
 

src/mplfinance/plotting.py

@@ -924,6 +924,13 @@ def _addplot_columns(panid,panels,ydata,apdict,xdates,config):
         width  = apdict['width'] if apdict['width'] is not None else 1.6*config['_width_config']['line_width']
         alpha  = apdict['alpha']
         ax.plot(xdates,ydata,linestyle=ls,color=color,linewidth=width,alpha=alpha)
+    elif aptype == 'step':
+        stepwhere = apdict['stepwhere']
+        ls = apdict['linestyle']
+        color  = apdict['color']
+        width  = apdict['width'] if apdict['width'] is not None else 1.6*config['_width_config']['line_width']
+        alpha  = apdict['alpha']
+        ax.step(xdates,ydata,where = stepwhere,linestyle=ls,color=color,linewidth=width,alpha=alpha)
     else:
         raise ValueError('addplot type "'+str(aptype)+'" NOT yet supported.')
 
@@ -1010,7 +1017,8 @@ def _auto_secondary_y( panels, panid, ylo, yhi ):
 def _valid_addplot_kwargs():
 
     valid_linestyles = ('-','solid','--','dashed','-.','dashdot','.','dotted',None,' ','')
-    valid_types = ('line','scatter','bar', 'ohlc', 'candle')
+    valid_types = ('line','scatter','bar', 'ohlc', 'candle','step')
+    valid_stepwheres = ('pre','post','mid')
 
     vkwargs = {
         'scatter'     : { 'Default'     : False,
@@ -1070,6 +1078,9 @@ def _valid_addplot_kwargs():
 
         'yscale'      : { 'Default'     : None,
                           'Validator'   : lambda value: _yscale_validator(value) },
+
+        'stepwhere'      : { 'Default'     : 'pre',
+                          'Validator'   : lambda value : value in valid_stepwheres },                  
     }
 
     _validate_vkwargs_dict(vkwargs)

tests/reference_images/addplot11.png

@@ -329,3 +329,28 @@ def test_addplot10(bolldata):
        print('result=',result)
     assert result is None
 
+def test_addplot11(bolldata):
+
+    df = bolldata[50:130].copy()
+
+    fname = base+'11.png'
+    tname = os.path.join(tdir,fname)
+    rname = os.path.join(refd,fname)
+    
+    df.loc[:,'trend'] = 0
+    df.loc[df['Close'] < df['Open'], 'trend'] = - 1
+    df.loc[df['Close'] > df['Open'], 'trend'] = 1
+    ap = mpf.make_addplot(df['trend'],panel=1,type='step',ylabel='simple trend')
+    mpf.plot(df,ylabel='OHLC',addplot=ap,savefig=tname)
+
+    tsize = os.path.getsize(tname)
+    print(glob.glob(tname),'[',tsize,'bytes',']')
+
+    rsize = os.path.getsize(rname)
+    print(glob.glob(rname),'[',rsize,'bytes',']')
+
+    result = compare_images(rname,tname,tol=IMGCOMP_TOLERANCE)
+    if result is not None:
+        print('result=',result)
+    assert result is None
+