Pandas Dataframe if statement using apply errors

Question

I am Currently trying to create IF statements to apply a class element to certain cells so I can style them using CSS. I currently can't use the styling options that pandas gives because I am using the .to_html function.

My table is as follows. {'Pwer':[-.3,-1.3,-2.4], 'Trend':[1.3,-1.3,-1.7]}

I tried

if((hist['Pwer']<0) & (hist['Trend']<0)):
            hist['Pwer']=hist['Pwer'].apply(lambda x:'<span class="Negative Trend_neg">{0}</span>'.format(x))

But it results in

The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(),     a.any() or a.all().

I'm not quite sure I understand what is going on even if I apply .all() to both hist['Pwer'] and hist['Trend']. Any help would be appreciative.

gabra · Accepted Answer · 2016-07-13 20:08:40Z

1

Something like this will work:

cond =  ((hist['Pwer']<0) & (hist['Trend']<0))
hist['Pwer'][cond] = hist['Pwer'][cond].apply(lambda x:'<span class="Negative Trend_neg">{0}</span>'.format(x))

The output is

                                           Pwer  Trend
0                                          -0.3    1.3
1  <span class="Negative Trend_neg">-1.3</span>   -1.3
2  <span class="Negative Trend_neg">-2.4</span>   -1.7

answered Jul 13, 2016 at 20:08

gabra

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jezrael · Accepted Answer · 2016-07-13 20:06:25Z

0

I think you need mask:

hist = pd.DataFrame({'Pwer':[-.3,-1.3,-2.4], 'Trend':[1.3,-1.3,-1.7]} )
print (hist)
    Pwer  Trend
0  -0.3    1.3
1  -1.3   -1.3
2  -2.4   -1.7

hist['Pwer']=hist['Pwer'].mask((hist['Pwer']<0) & (hist['Trend']<0), 
                                hist['Pwer'].apply(lambda x:'<span class="Negative Trend_neg">{0}</span>'.format(x))) 
print (hist)
                                           Pwer  Trend
0                                          -0.3    1.3
1  <span class="Negative Trend_neg">-1.3</span>   -1.3
2  <span class="Negative Trend_neg">-2.4</span>   -1.7

answered Jul 13, 2016 at 20:06

jezrael

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