Loop through multiple dicts in list, while assigning values to incremental variables - python

Question

x = [
   {'id': 'e5015', 'price': '2001.00000000', 'size': '0.30000000', 'time_in_force': 'GTC'}, 
   {'id': 'bdd3d', 'price': '2000.00000000', 'size': '0.10000000', 'time_in_force': 'GTC'}, 
   {'id': '32c60', 'price': '2000.00000000', 'size': '0.01770613', 'time_in_force': 'GTC'}
   {**insert varying number of additional dicts here**}
]

How do we loop through this list of dicts, and assign them to incremental variables depending on how many dicts there are? (eg. z1, z2, z3, z4, z5, etc)

z1 = x[0]["price1"]
z2 = x[0]["price2"]
z3 = x[0]["price3"]
z4 = x[0]["price4"]
...etc...
z9 = x[0]["price9"] # If it exists

Why do you think you want to do this? What advantage could multiple variables possibly have over a list in this case? — Paul M., Jun 25 '21 at 19:32
`x[0]["price1"]` will fail with a KeyError. You're neither looping through the list of dicts (it's always `x[0]`), nor getting a dict item out (since price1, price2, price3 etc don't exist as keys in the dicts). — 9769953, Jun 25 '21 at 19:33
They could possibly stay in the list, and perform the required math functions, but we would still need to be able to grab different 'price' and 'size' VALUES from dicts in the list that have identical KEYS (eg. 'price' is the same in each dict, but value of 'price' is not.) — Dakota Mac Dylan Carter MacBai, Jun 25 '21 at 19:38
regarding z1, z2... z9 - check https://stackoverflow.com/questions/1373164/how-do-i-create-variable-variables It's a bad idea, use data structure — buran, Jun 25 '21 at 19:51

score 1 · Answer 1 · answered Jun 25 '21 at 19:36

How do we loop through this list of dicts, and assign them to incremental variables...

The answer is: You don't. It looks like you're trying to iterate over the dictionaries, and only retain price information. So, why not make a list of prices?

prices = [d["price"] for d in x]

chatax · Accepted Answer · 2021-06-25T20:49:28.063

1

Use list comprehension and list indices instead to get your price variables

prices = [d['price'] for d in x]
z1 = prices[0]
z2 = prices[1]
# ...etc

edited Jun 25 '21 at 20:49

answered Jun 25 '21 at 19:37

chatax

990
3
17

list index out of range - (when trying to assign z5 IF z5 does not exist in list) – Dakota Mac Dylan Carter MacBai Jun 25 '21 at 19:49
1

I don't understand why you would want to manually assign variables for each price possible – chatax Jun 25 '21 at 19:52
True. We can keep the DICTs, but how would we check how many items exist in DICTs? – Dakota Mac Dylan Carter MacBai Jun 25 '21 at 19:54
1

by using `len(x)` – chatax Jun 25 '21 at 19:55
so after we find out len(prices) = 6, how do we set up a function that can use prices[1] through prices[6], no more no less? ( If len(prices) = 6, run through 6 times ) – Dakota Mac Dylan Carter MacBai Jun 25 '21 at 20:09
prices[0] through prices[5] since python indexing starts at 0 – chatax Jun 25 '21 at 20:11

Loop through multiple dicts in list, while assigning values to incremental variables - python

2 Answers2