当使用两行时,操作数不能一起广播错误 [英] Operands could not be broadcast together error when two rows used
问题描述
使用以下数据:
import datetime,numpy as np,pandas as pd
nan = np.nan
a = pd.DataFrame( {'price': {datetime.time(9, 0): 1, datetime.time(10, 0): 0, datetime.time(11, 0): 3, datetime.time(12, 0): 4, datetime.time(13, 0): 7, datetime.time(14, 0): 6, datetime.time(15, 0): 5, datetime.time(16, 0): 4, datetime.time(17, 0): 0, datetime.time(18, 0): 2, datetime.time(19, 0): 4, datetime.time(20, 0): 7}, 'reversal': {datetime.time(9, 0): 1, datetime.time(10, 0): nan, datetime.time(11, 0): nan, datetime.time(12, 0): nan, datetime.time(13, 0): nan,
datetime.time(14, 0): 6.0, datetime.time(15, 0): nan, datetime.time(16, 0): nan, datetime.time(17, 0): nan, datetime.time(18, 0): nan, datetime.time(19, 0): nan, datetime.time(20, 0): nan}})
a['target_hit']=nan;
a['target_miss']=nan;
a['reversal1']=a['reversal']+1;
a['reversal2']=a['reversal']-a['reversal'];
a.sort_index(1,inplace=True);
我创建一个子集,如下所示:
I create a subset as follows:
hit = a.ix[:,:-2].dropna()
hit
哪个给出的输出显示匹配的两行:
Which gives output showing two rows that match:
price reversal reversal1 reversal2
09:00:00 1 1.0 2.0 0.0
14:00:00 6 6.0 7.0 0.0
然后我尝试使用这些行与以下内容进行匹配时,出现此错误ValueError: operands could not be broadcast together with shapes (2,) (12,)
When I then try to use these rows to match against the following I get this error ValueError: operands could not be broadcast together with shapes (2,) (12,)
takeBoth = False
targetIsHit,targetIsMiss = False,False
if takeBoth:
targetHit = a[(hit['reversal1'].values==a['price'].values) & (hit['reversal1'].index.values<a['price'].index.values)];
targetMiss = a[(hit['reversal2'].values==a['price'].values) & (hit['reversal2'].index.values<a['price'].index.values)];
targetIsHit,targetIsMiss = not targetHit.empty, not targetMiss.empty
else:
targetHit = a[(hit['reversal1'].values==a['price'].values) & (hit['reversal1'].index.values<a['price'].index.values)];
targetIsHit = not targetHit.empty
if not targetIsHit:
targetMiss = a[(hit['reversal2'].values==a['price'].values) & (hit['reversal2'].index.values<a['price'].index.values)];
targetIsMiss = not targetMiss.empty
if targetIsHit:a.loc[hit.index.values,"target_hit"] = targetHit.index.values;
if targetIsMiss:a.loc[hit.index.values,"target_miss"] = targetMiss.index.values;
如果hit = a.ix[:,:-2].dropna()
仅产生一行,则不会出现此错误.阅读有关此内容的信息后,我发现这可能是由于广播规则所致.
I do not get this error if hit = a.ix[:,:-2].dropna()
only produces one row. After reading about this I see that this is possibly due to the broadcasting rule.
我应该遍历hit
中的行来避免这种情况吗?还有其他关于如何解决此问题的建议吗?
Should I be iterating over the rows in hit
to avoid this? Any other suggestions on how to fix this please?
推荐答案
是的,它必须是for循环的...现在,我将其更改为从命中或未命中优先选择.
Yup it has to be for loop... Now I changed it to choose first from hit or miss.
import datetime,numpy as np,pandas as pd;
nan = np.nan;
a = pd.DataFrame( {'price': {datetime.time(9, 0): 1, datetime.time(10, 0): 0, datetime.time(11, 0): 3, datetime.time(12, 0): 4, datetime.time(13, 0): 7, datetime.time(14, 0): 6, datetime.time(15, 0): 5, datetime.time(16, 0): 4, datetime.time(17, 0): 0, datetime.time(18, 0): 2, datetime.time(19, 0): 4, datetime.time(20, 0): 7}, 'reversal': {datetime.time(9, 0): 1, datetime.time(10, 0): nan, datetime.time(11, 0): nan, datetime.time(12, 0): nan, datetime.time(13, 0): nan,
datetime.time(14, 0): 6.0, datetime.time(15, 0): nan, datetime.time(16, 0): nan, datetime.time(17, 0): nan, datetime.time(18, 0): nan, datetime.time(19, 0): nan, datetime.time(20, 0): nan}});
a['target_hit']=a['target_miss']=nan;
a['reversal1']=a['reversal']+1;
a['reversal2']=a['reversal']-a['reversal'];
a.sort_index(1,inplace=True);
hits = a.ix[:,:-2].dropna();
for row,hit in hits.iterrows():
forwardRows = [row]<a['price'].index.values
targetHit = a.index.values[(hit['reversal1']==a['price'].values) & forwardRows][0];
targetMiss = a.index.values[(hit['reversal2']==a['price'].values) & forwardRows][0];
if targetHit>targetMiss:
a.loc[row,"target_miss"] = targetMiss;
else:
a.loc[row,"target_hit"] = targetHit;
print '#'*50
print a
'''
##################################################
##################################################
price reversal reversal1 reversal2 target_hit target_miss
09:00:00 1 1.0 2.0 0.0 NaN 10:00:00
10:00:00 0 NaN NaN NaN NaN NaN
11:00:00 3 NaN NaN NaN NaN NaN
12:00:00 4 NaN NaN NaN NaN NaN
13:00:00 7 NaN NaN NaN NaN NaN
14:00:00 6 6.0 7.0 0.0 NaN 17:00:00
15:00:00 5 NaN NaN NaN NaN NaN
16:00:00 4 NaN NaN NaN NaN NaN
17:00:00 0 NaN NaN NaN NaN NaN
18:00:00 2 NaN NaN NaN NaN NaN
19:00:00 4 NaN NaN NaN NaN NaN
20:00:00 7 NaN NaN NaN NaN NaN
'''
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