CODEWITHSUNDEEP
pythonrandom
Drazen
Drazen

Reputation: 67

I am creating a list and need to return the initial value

Here is my code:

import random

def stock_sim(price,time,mu,std):
    y=range(time)
    for i in y:
        y[i]=price+random.lognormvariate(mu,std)
    return y

print(stock_sim(100,5,0,.2))

It returns:

[101.44054391531468, 100.73246087607879, 101.00880842134261, 101.14332126597128, 100.79412638906443]

I need it to return:

[100, 101.44054391531468, 100.73246087607879, 101.00880842134261, 101.14332126597128]

The first value should be the intial price on first day and then the following 4 changed prices.

Upvotes: 0

Views: 51

Answers (2)

user2489252
user2489252

Reputation:

One possibility would be

def stock_sim(price,time,mu,std):
    return [price]+[price + random.lognormvariate(mu,std) for i in range(time)]

There are many other ways, one could be to insert an item to the left, or create the list beforehand in the other solutions.

def stock_sim(price,time,mu,std):
    temp = [price + random.lognormvariate(mu,std) for i in range(time)]
    temp.insert(0,price)
    return temp

I am not sure how big your lists will grow and if performance can be an issue. In this case a deque would be the better solution

from collections import deque
def stock_sim(price,time,mu,std):
    temp = deque([price + random.lognormvariate(mu,std) for i in range(time)])
    temp.appendleft(price)
    return temp

Upvotes: 0

Padraic Cunningham
Padraic Cunningham

Reputation: 180482

Just keep a separate list and add price first:

def stock_sim(price,time,mu,std):
    y = []
    y.append(price)
    for i in range(time):
        y.append(price+random.lognormvariate(mu,std))
    return y

Upvotes: 2

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