KeyError Traceback using for+if in python

Question

I am a newbie on python. I am trying to check the results of a test and train and I have to compare my predictions with the actual test results (data_train). Data_train is a dictionary as shown in the image below . The prediction is an array like this

The code aims to counts the consistent classifications between prediction and test results.

consistent=0
inconsistent=0
​
for i in np.linspace(1,len_test,len_test):
    if  data_train['class'][i] == predictions[i]:
        consistent=consistent+1
    else:
        inconsistent=inconsistent+1

I have this error, what does it means? I don't know how to catch error like this one in python

---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
~\anaconda4\lib\site-packages\pandas\core\indexes\base.py in get_loc(self, key, method, tolerance)
   3360             try:
-> 3361                 return self._engine.get_loc(casted_key)
   3362             except KeyError as err:

~\anaconda4\lib\site-packages\pandas\_libs\index.pyx in pandas._libs.index.IndexEngine.get_loc()

~\anaconda4\lib\site-packages\pandas\_libs\index.pyx in pandas._libs.index.IndexEngine.get_loc()

pandas\_libs\hashtable_class_helper.pxi in pandas._libs.hashtable.PyObjectHashTable.get_item()

pandas\_libs\hashtable_class_helper.pxi in pandas._libs.hashtable.PyObjectHashTable.get_item()

KeyError: 1

The above exception was the direct cause of the following exception:

KeyError                                  Traceback (most recent call last)
~\AppData\Local\Temp/ipykernel_10076/1764309407.py in <module>
      1 for i in np.linspace(1,len_test,len_test):
----> 2     a=data_train['class'][i]
      3     b=predictions[i]
      4     if  a == b:
      5         consistent=consistent+1

~\anaconda4\lib\site-packages\pandas\core\series.py in __getitem__(self, key)
    940 
    941         elif key_is_scalar:
--> 942             return self._get_value(key)
    943 
    944         if is_hashable(key):

~\anaconda4\lib\site-packages\pandas\core\series.py in _get_value(self, label, takeable)
   1049 
   1050         # Similar to Index.get_value, but we do not fall back to positional
-> 1051         loc = self.index.get_loc(label)
   1052         return self.index._get_values_for_loc(self, loc, label)
   1053 

~\anaconda4\lib\site-packages\pandas\core\indexes\base.py in get_loc(self, key, method, tolerance)
   3361                 return self._engine.get_loc(casted_key)
   3362             except KeyError as err:
-> 3363                 raise KeyError(key) from err
   3364 
   3365         if is_scalar(key) and isna(key) and not self.hasnans:

KeyError: 1.0

Answer 1

I'm not entirely sure of the code's context, but it seems you're using NumPy. As I understand it, referencing an array element can only be done using an integer (or slices, ellipses etc.), but not strings. You appear to be attempting to reference using the string 'class' and I don't understand why. My suggestion would be to remove the ['class'] reference and simply use the integer reference, such as: a=data_train[i]