CODEWITHSUNDEEP
pythontypes
rosepalette
rosepalette

Reputation: 31

Python differentiate data type

I have 2 different kind of list in python:
1. test1 = ['abc', 'cde', 'fgh']
2. test2 = [{'name': 'me', 'address': 'usa'}]

Both appear to be a list when i check the type:

if test1 is list: --> true
if test2 is list: --> true

is there any way i can check if it is a list of string or list of dictionary?

Upvotes: 0

Views: 90

Answers (7)

LNGZL
LNGZL

Reputation: 3

You can use something like the following:

test1 = ["abc", "cde", "fgh"]
if type(test1) is list:
  print("Hello")
# Hello

What it will do is use the type(arg) function where you can pass a variable or data directly to get the type as an output.

For example type("test") will make it return <type 'str'> which means it's a string.

Upvotes: 0

charalagou
charalagou

Reputation: 38

There are mainly two ways to do this, either with type() or with isinstance(). In case you don't know the exact type of list you have it is preferred to use the former (type()) otherwise the latter is more suitable. My solution addresses the first case and it assumes that the list may contain more than one types. 

test1 = ['abc', 'cde', 'fgh']
test2 = [{'name': 'me', 'address': 'usa'}]
test3 = ['abc', 'cde', 3, [2, 1]]
print("Test1 is a list of ", set([type(elem) for elem in test1])) #str
print("Test2 is a list of ", set([type(elem) for elem in test2])) #dict
print("Test3 is a list of ", set([type(elem) for elem in test3])) #str, int, list

I hope this answers your question :-)

Upvotes: 0

Nigel Feasey
Nigel Feasey

Reputation: 79

I would check the first element of each list to determine what kind of list it is. For example:

list1_type = typeof(list1[0])

list2_type = typeof(list2[0])

Of course, a list doesn't have to have all the same type, so without checking every element, you can't know for sure.

Upvotes: 0

timgeb
timgeb

Reputation: 78790

Well, test1 and test2 are lists, which you can check via

>>> isinstance(test1, list)                                                     
True
>>> isinstance(test2, list)                                                     
True

(test1 is list and test2 is list actually return False, because neither are the builtin list class.)

What might be confusing you is that test2 is a list with only one element, and that element is a dictionary.

>>> test2[0]                                                                    
{'name': 'me', 'address': 'usa'}
>>> type(test2[0])                                                              
dict

If you want to know all the types a list holds, you can do

>>> l = [1, '2', []]                                                            
>>> set(map(type, l))                                                           
{int, list, str}
# alternative
>>> set(type(x) for x in l)                                                     
{int, list, str}

Upvotes: 0

chepner
chepner

Reputation: 532418

Yes, they are both lists, period; type doesn't take into consideration what is in the list.

You can use type hints to restrict what should be in the list, but these only serve to document the intended use, or by tools like mypy; they don't affect what you can actually put in the list.

from typing import List, Dict


test1: List[str] = ['abc', 'cde', 'fgh']
test2: List[Dict[str,str]] = [{'name': 'me', 'address': 'use']

def foo(x: List[str]):
    ...

mypy will flag as an error any attempt to pass test1 to foo, but that's allowed when you actually run the code.

mypy would also flag as an error something like

test3: List[str] = ['foo', 1]

since 1 is not a str, but again, at runtime that is perfectly legal.

Upvotes: 1

Basu_C
Basu_C

Reputation: 410

Try this snippet:

for item in test1:
   print(type(item))

Similar snippet for test2.

Upvotes: 0

Tin Nguyen
Tin Nguyen

Reputation: 5330

To check if an object is of a class you usually use isinstance

>>> isinstance("hello", str)
True
>>> isinstance({}, dict)
True
>>> isinstance([], list)
True
>>> isinstance(5, int)
True
>>> isinstance("hello", int)
False

Upvotes: 0

Related Questions