KeyError: 'sepal_length'

This error occurs when the key 'sepal_length' is not found in a dictionary or a pandas dataframe.

For example, suppose you have a dictionary called 'iris' that contains information about the flowers. If you try to access the value of 'sepal_length' from this dictionary using the key 'sepal_length', but the key is not present in the dictionary, then you will get a KeyError: 'sepal_length'.

Here's an example code snippet that can produce this error:

iris = {'species': 'setosa', 'petal_length': 1.4, 'petal_width': 0.2}

print(iris['sepal_length'])  # KeyError: 'sepal_length'

In this example, the key 'sepal_length' is not present in the 'iris' dictionary, so trying to access it will result in a KeyError.