在所有 Dataframe 行中应用函数的返回值

Question

I am trying to assign a value from a function in all rows of a Dataframe in a new column. ie the df below should contain new column called random number with the random number generated in the get_random() function.

import pandas as pd
from random import random

def get_random():
    return random()

d = {'col1': [1, 2], 'col2': [3, 4]}
df = pd.DataFrame(data=d)

I tried the below, but I get the error get_random takes 0 positional arguments

df['random number'] = df.apply(get_random)

Answer 1

You can either do

df['random number'] = df.apply(lambda x: random())

or change get_random to

def get_random(x):
    return random()

Answer 2

Just change the function random :

def get_random(x):
    return random()

as apply expects the function to take an input.

Answer 3

您可以使用列表理解

df['random number'] = [get_random() for i in range(len(df))]