Pass array as parameter python-CodePudding

I am trying to pass all the arrays such as molecularWeight(concentration,time) `

concentration_time = np.array([[0,83],
                               [0.04,89],
                               [0.06,95],
                               [0.08,104],
                               [0.1,114],
                               [0.12,126],
                               [0.14,139],
                               [0.16,155],
                               [0.20,191]])


concentration = [item[0] for item in concentration_time]
time = [item[1] for item in concentration_time]


t0 = 83

def molecularWeight(c,t):
    answer = ((t/t0)-1)/c
    return answer

molecularWeight(concentration,time)

I was expecting to get an output with 9 different outputs. I want to pass all pairs for c and t and get an output for each.

I get the desired output when I manually pass the values:molecularWeight(0.04,89.0) but not when I try to pass all of them using the previously defined variables: molecularWeight(concentration,time) ERROR:

TypeError: unsupported operand type(s) for /: 'list' and 'int'

CodePudding user response：

Lists in python do not support addition/subtraction/other mathematical operations.
You need to either use numpy, or explicitly do the operations within a list-comprehension (or loop) over the zipped element pairs...

For instance:

import numpy as np

def molecularWeight(c,t):
    c = np.array(c)
    t = np.array(t)
    answer = ((t/t0)-1)/c
    return answer

molecularWeight(concentration,time)

or conversely:

def molecularWeight(c,t):
    try:
        answer = ((t/t0)-1)/c
    except TypeError:
        answer = [((t_/t0)-1)/c_ for c_, t_ in zip(c, t)]
    return answer

molecularWeight(concentration,time)

Note that you started off with a numpy array, so you could just stick to that from the start, leave the function as you defined it, but make sure to pass in numpy-arrays and not lists:

concentration = concentration_time[:, 0]
time = concentration_time[:, 1]

CodePudding user response：

add safety for your division (1e-9) here for example to avoid div to zero

concentration ,time = concentration_time[:,0], concentration_time[:,1]
t0 = 83
def molecularWeight(c,t):
    return ((t / t0) - 1) / (c   1e-9)

molecularWeight(concentration,time)

CodePudding user response：

This is probably what you want, if I'm understanding correctly.

You are correctly giving the list to the function as an input, but not iterating over it correctly.

def molecularWeight(inputs):
    answers = []

    for c, t in inputs: 
        answer = ((t/t0)-1)/c
        answers.append(answer)

    return answers