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I know that[:,-1] means in pandas to use every row element and the last column element. But currently I see in the pandas documentation this one [::-1] and I wonder the meaning behind it?

Thanks

ddd
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1 Answers1

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The optional 3rd number in the __getitem__ is the step. For pandas dataframes and series, as with python lists, when the third value is -1, you get the items in reverse order. For example

import pandas as pd

df = pd.DataFrame([[1], [2]])
# prints a row with 1, then a row with 2
print(df)
# prints a row with 2, then a row with 1
print(df[::-1])
Mahesh Vashishtha
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