24 Python: Function as a String

24.1 Function as a character/string

Python does not have a direct equivalent to R’s do.call or match.fun.
However, one can achieve a similar effect using a dictionary to map function names to their actual function objects, as shown in the previous response.
An alternative option is to use partial function of functools library.

24.2 Data

Code

import numpy as np

A = np.array([11, 12, np.nan, 14, 15])

24.3 Option 1: Using mapping function

Code

def fn_N(x, na_rm=False):
    xn = len(x) - np.isnan(x).sum() if na_rm else len(x)
    return xn

def fn_sum(x, na_rm=False):
    return np.nansum(x) if na_rm else np.sum(x)

def fn_mean(x, na_rm=False):
    xn = fn_N(x, na_rm=na_rm)
    xsum = fn_sum(x, na_rm=na_rm)
    xmean = xsum / xn
    return xmean

def fn_call(func_name, *args, **kwargs):
    function_map = {
        'fn_mean': fn_mean,
    }
    
    func = function_map.get(func_name)
    if func is None:
        raise ValueError("Function not found")
    
    return func(*args, **kwargs)

24.4 Example

Code

fn_call('fn_mean', A, na_rm=True)

24.5 Option 2: Using library `functools`

Code

import numpy as np
from functools import partial

def fn_N(x, na_rm=False):
    xn = len(x) - np.isnan(x).sum() if na_rm else len(x)
    return xn

def fn_sum(x, na_rm=False):
    return np.nansum(x) if na_rm else np.sum(x)

def fn_xmean(x, na_rm=False):
    xn = fn_N(x, na_rm=na_rm)
    xsum = fn_sum(x, na_rm=na_rm)
    xmean = xsum / xn
    return xmean

# Using functools.partial to create a function with preset arguments
def fn_call(func_name, *args, **kwargs):
    func = globals().get(func_name)
    if func is None:
        raise ValueError("Function not found")
    
    partial_func = partial(func, *args, **kwargs)
    return partial_func()

24.6 Example

Code

fn_call('fn_mean', A, na_rm=True)