CODEWITHSUNDEEP
python-3.xpandasdataframe
daiyue
daiyue

Reputation: 7448

pandas Series determine which key(s) does not exist in a dict

I have the following df,

currency    value
USD         1.0
EUR         2.0
RMB         3.0

and I get a dict for containing exchange rates,

rates = {'GBP': 0.76, 'USD': 1.0, 'CNY': 6.6}

when I do

df['value'].div(df['currency'].map(rates))

how do I know/get which value in currency did not get map to rates, like a KeyError, I tried

try:
    df['amount'] = df.['value'].div(df['currency'].map(rates))
except KeyError as e:
    print('Key {} does not exist in the exchange rates dictionary'.format(e.args[0]))

but no errors were thrown. I am wondering how to do that.

Upvotes: 1

Views: 686

Answers (1)

jezrael
jezrael

Reputation: 862511

Your code working and if no key in dict get NaNs in column value.

So need all currency with NaNs after map:

a = df['value'].div(df['currency'].map(rates))

b = df.loc[a.isnull(), 'currency']
print (b)
1    EUR
2    RMB
Name: currency, dtype: object

Upvotes: 1

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