What the best way to get structured array / dataframe like structures in Numba?

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I have a numpy array that I reference by column, e.g., df['x'], df['y'].

What is the best way to give this to Numba so I can run the function in nopython mode?

Or what is the best way to deal with dataframes in Numba, so I can access a column by name?

numba pandas jit numpy python
1 Answers

Supply 1d arrays as arguments

numba is designed to work with NumPy arrays directly. So you should not look to feed a dataframe or structured array to a numba function. You can feed the arrays as separate arguments. For example:

from numba import njit

@njit
def func(A, B):
    # some logic
    arr = A + B
    return arr

df['z'] = func(df['x'].values, df['y'].values)

Unpack 2d array within numba function

This is a special case where your dataframe series all have the same type. Check df.dtypes if you are not sure of your series types. You can feed a single array and perform the unpacking within numba:

@njit
def func(df_values):
    A, B = df_values[:, 0], df_values[:, 1]
    # some logic
    arr = A + B
    return arr

df['z'] = func(df[['x', 'y']].values)
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