if condition + check isnull() is true

Question

I have a df that looks like this:

     carry_dt    sedol    prime_broker_id  legal_entity   strategy  NewCarryRate  
716   2018-01-02  B1T84Z4    CITI             USSA-AGG      USSA       NaN

I would like to check if there are any NaN values in the column 'NewCarryRate' and replace them

I created an if condition:

 if (allHoldings['NewCarryRate'].iloc[[i]].isnull())==True:
        allHoldings['NewCarryRate'].values[i]= 100

I get an error saying:

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

I know I can use np.where but I find it easier to use if condition here because I can add more rows under the if condition if I wanted to.

Many Thanks for your help

You use a double array at `.iloc[[i]]` don't you mean `.iloc[i]`? And you dont have to use the `== True` it's redundant — Ron Nabuurs, May 18 '18 at 09:24
@Ron Thank you for you answer i did `.iloc[[i]]` to select the row i. is it not correct? also when I do `allHoldings['NewCarryRate'].iloc[i].isnull())` i get an error — SBad, May 18 '18 at 09:28
I'm not sure about what is correct, I've never used pandas. But what are you trying to accomplish with it? Do you want to check if the whole row is null? — Ron Nabuurs, May 18 '18 at 09:31
And have a look at this [answer](https://stackoverflow.com/a/36922103/5686835) — Ron Nabuurs, May 18 '18 at 09:34
I am looking to check if the column['NewCarryRate'] of row i is NaN — SBad, May 18 '18 at 10:48
@SBad actually, according to your description, you're just looking to replace such values by 100; explicitly check if row i is NaN is not your end in itself. — Ami Tavory, May 18 '18 at 11:11

score 2 · Accepted Answer · answered May 18 '18 at 10:20

You can just use pd.Series.fillna for this:

allHoldings['NewCarryRate'].fillna(100, inplace=True)

The entire if clause is unnecessary - fillna does this. The reason you're getting this error is that

if (allHoldings['NewCarryRate'].iloc[[i]].isnull())==True:

it can be true for some entries and false for some; the interpreter can't know if to perform the clause or not.

if condition + check isnull() is true

1 Answers1