2

I have a list of names and using random.choice(), I am able to get a random element from the list. Now I am trying to figure out at what index that given element sits in the list. This is what I have so far:

import random

x = ['Jess','Jack','Mary','Sophia','Karen','Addison','Joseph','Eric','Ilona','Jason']
y = random.choice(x)
print(y)
Tomerikoo
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Chubee
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    x.index(y) will give you the index. – Joe Ferndz Sep 24 '20 at 06:15
  • does the list contain duplicates? – deadshot Sep 24 '20 at 06:15
  • It does not but would it matter? – Chubee Sep 24 '20 at 06:16
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    Yes it will matter. `index` only returns the first occurrence in the list. – PacketLoss Sep 24 '20 at 06:16
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    list.index(element, start,end) is the command. So if you dont provide start or end, then it will find the first occurrence. If there are duplicates, it won't find the next one unless you specify the start position – Joe Ferndz Sep 24 '20 at 06:19
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    Does this answer your question? [How to randomly select an item from a list?](https://stackoverflow.com/questions/306400/how-to-randomly-select-an-item-from-a-list) See this answer there: https://stackoverflow.com/a/12373205/7851470 – Georgy Sep 24 '20 at 07:22

4 Answers4

8

You can use list.index():

x.index(y)

This will return the first index in the list where it finds a match. However, this will not return the correct index if you have duplicates in your list.

A better way to handle this, in the case you have duplicates would be to randomise the index instead of the value. As you will always store the correct index you're referencing and not the first occurance.

y = random.randint(0, len(x))
#3

x[y]

#Sophia
Tomerikoo
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PacketLoss
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6

You can use randrange

import random

x = ['Jess','Jack','Mary','Sophia','Karen','Addison','Joseph','Eric','Ilona','Jason']
i = random.randrange(len(x))

print(i, x[i])

Example output:

7 Eric

Jonas Byström
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woblob
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2

This can be done in 2 ways.

Method 1

  1. Find the length of the list (n) and then choose a random integer from 0-n as K.
  2. Return the element in the list at kth index and the index k
import random
x = ['Jess','Jack','Mary','Sophia','Karen','Addison','Joseph','Eric','Ilona','Jason']
k = random.randrange(len(x)) # k is the random index
print(x[k], k) # x[k] will be the random element

Method 2

Pick the random element using random.choice and then use list.index to find the index

value= random.choice(x)
index= x.index(value)

Note 1: This doesn't work well when duplicate elements are present in the list

Most preferred way would be Method 1

You can also use random.choice to get the index

index = random.choice(range(len(x)))
value = x[index]

But this is a bit slow compared to random.randange

Dileep Kumar
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0

You can give y = x.index(random.choice(x)) This will assign the index to y

Joe Ferndz
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