python: pandas.DataFrame，how to avoid keyerror?

Question

In C++, when I can't find a keyword in a table, it will return NULL or in database it will return a empty table, so the program continues to run. But in python, it throws an exception, and interrupts my program. Can I avoid that? for example, I have such a DataFrame named datevar :

(datetimeIndex)   value
2001-01-01           1
2001-01-02           1
2001-01-03           3
....

v = datevar.xs('2000-01-01', level='date') # of course "keyError"
v = datevar.loc['2000-01-01' , :]          # of course "keyError"

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– jezrael, Commented May 16, 2018 at 6:11

lihua · Accepted Answer · 2018-05-16 08:00:55Z

5

I think you can check if the index is existed in the df's index or the columns before you get the value of that key.

df = pd.read_clipboard()
df
Out[6]: 
  (datetimeIndex)  value
0      2001-01-01      1
1      2001-01-02      1
2      2001-01-03      3
key = "2000-01-01"
if key in df.index:
    v = df.xs('2000-01-01', level='date')  # of course "keyError"
    v = df.loc['2000-01-01', :]  # of course "keyError"
else:
    v = None
v

answered May 16, 2018 at 8:00

community wiki

lihua

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1 Comment

Vishal Kumar Sahu Over a year ago

Like dict has get method there should be some method which doesn't hurt and halt.

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