Generator object is not subscriptable ошибка

Your x value is is a generator object, which is an Iterator: it generates values in order, as they are requested by a for loop or by calling next(x).

You are trying to access it as though it were a list or other Sequence type, which let you access arbitrary elements by index as x[p + 1].

If you want to look up values from your generator’s output by index, you may want to convert it to a list:

x = list(x)

This solves your problem, and is suitable in most cases. However, this requires generating and saving all of the values at once, so it can fail if you’re dealing with an extremely long or infinite list of values, or the values are extremely large.

If you just needed a single value from the generator, you could instead use itertools.islice(x, p) to discard the first p values, then next(...) to take the one you need. This eliminate the need to hold multiple items in memory or compute values beyond the one you’re looking for.

import itertools

result = next(itertools.islice(x, p))

If you’re a Python programmer, you might have encountered the “typeerror generator object is not subscriptable” error message.

This error message can be confusing and frustrating, specifically if you are not sure why it is occurring.

In this article, we will explain to you what a generator object is and why it is not subscriptable.

We will also provide examples of this error and how to resolve it.

Why does the “TypeError: generator object is not subscriptable” error occur?

The “TypeError: generator object is not subscriptable” error typically occurs because when you attempt to use square brackets to access individual elements of a generator object.

Generator objects are not subscriptable, it means that you cannot use square brackets to access them.

Subscripting in Python

In Python, subscripting is an action to access individual elements of a sequence, such as a list or a tuple.

To subscript a sequence, you can use square brackets after the sequence name.

In the Inside of the square brackets, you can put the index of the element you want to access.

For example, if you have a list named my_list, and you want to access the first element of the list.

For example, you will use the following code:

my_list = [1, 2, 3, 4, 5]
print(my_list[0])

Output:

C:UsersDellPycharmProjectspythonProjectvenvScriptspython.exe C:UsersDellPycharmProjectspythonProjectmain.py
1

Common Causes of typeerror: generator object is not subscriptable

Here are the two common causes of the error:

Causes 1: Attempting to Index a Generator Object

One of the common cause of the “TypeError: generator object is not subscriptable” error is attempting to access individual elements of a generator object using square brackets.

Since generator objects are not subscriptable, this will raise a TypeError.

For example, we will consider the following code:

def country_generator():
    yield 1
    yield 2
    yield 3

gen = country_generator()
print(gen[0])

In this example code, we define a generator function that yields the numbers 1, 2, and 3.

Then, we create a generator object from this function and attempt to access the first element of the generator using square brackets.

The output will be typeerror:

C:UsersDellPycharmProjectspythonProjectvenvScriptspython.exe C:UsersDellPycharmProjectspythonProjectmain.py
Traceback (most recent call last):
File “C:UsersDellPycharmProjectspythonProjectmain.py”, line 7, in
print(gen[1])
TypeError: ‘generator’ object is not subscriptable

Causes 2: Attempting to Slice a Generator Object

Another common cause of the “TypeError: generator object is not subscriptable” error is attempting to slice a generator object using the colon operator.

Since generator objects are not subscriptable, this will also raise a TypeError.

For example:

def my_generator():
    yield 1
    yield 2
    yield 3

gen = my_generator()
print(gen[0:2])

In this example code, we define a generator function that yields the numbers 1, 2, and 3.

Then, we create a generator object from this function and attempt to slice the generator using the colon operator.

The output will raises a TypeError since generator objects do not support slicing.

C:UsersDellPycharmProjectspythonProjectvenvScriptspython.exe C:UsersDellPycharmProjectspythonProjectmain.py
Traceback (most recent call last):
File “C:UsersDellPycharmProjectspythonProjectmain.py”, line 7, in
print(gen[0:2]) # Output: TypeError: ‘generator’ object is not subscriptable
TypeError: ‘generator’ object is not subscriptable

How to solve the typeerror generator object is not subscriptable error?

Here are the two solutions to solve the typeerror generator object is not subscriptable error.

Solution 3: Convert Generator Object to List or Tuple

The first solution to solve the generator’ object is not subscriptable error is to convert the generator object to a list or a tuple.

Since lists and tuples are subscriptable, you can use square brackets to access individual elements of the sequence.

For example:

def my_generator():
    yield 1
    yield 2
    yield 3

gen = my_generator()
my_list = list(gen)
print(my_list[0])

In this example code, we define a generator function that yields the numbers 1, 2, and 3.

Then, we create a generator object from this function and convert it to a list using the list() function.

Finally, we access the first element of the list using square brackets.

The output will successfully execute:

C:UsersDellPycharmProjectspythonProjectvenvScriptspython.exe C:UsersDellPycharmProjectspythonProjectmain.py
1

Solution 2: Use Next Function Instead of Subscripting

The last solution to solve the “TypeError: generator object is not subscriptable” error is to use the next() function to iterate over the generator object instead of subscripting it.

The next() function returns the next value in the generator sequence each time it is called.

For example:

def my_generator():
    yield 1
    yield 2
    yield 3

gen = my_generator()
print(next(gen))
print(next(gen))
print(next(gen))

In this example code, we define a generator function that yields the numbers 1, 2, and 3.

Then, we create a generator object from this function and use the next() function to iterate over the generator and print each value.

Output:

C:UsersDellPycharmProjectspythonProjectvenvScriptspython.exe C:UsersDellPycharmProjectspythonProjectmain.py
1
2
3

Additional Resources

The following are the articles we’ve explained on how to solve the typeerror in python:

• Typeerror not supported between instances of str and int
• Typeerror: ‘float’ object is not subscriptable [SOLVED]
• Typeerror: int object does not support item assignment [SOLVED]
• typeerror: ‘_environ’ object is not callable

Conclusion

In this article, we explained what the “TypeError: ‘generator’ object is not subscriptable” error means.

How it can occur, and how you can fix it. We showed that generator objects are not subscriptable.

It means that you cannot use square brackets to access individual elements of the sequence.

Instead, you can convert the generator object to a list or a tuple, or you can use the next() function to iterate over the generator object.

FAQs

In Python, you cannot access values inside a generator object using indexing syntax.

A generator function returns a generator object, an iterator containing a sequence of values. We can access the values in a generator object using a for loop or by calling next().

We can solve this error by converting the generator object to a list using the built-in list() method.

For example,

# A generator function
def generator_func():
    yield 1
    yield 2
    yield 3
   
# x is a generator object
x = list(generator_func())

print(x[0])

This tutorial will go through how to solve the error with code examples.

TypeError: ‘generator’ object is not subscriptable

Let’s break up the error message to understand what the error means. TypeError occurs whenever you attempt to use an illegal operation for a specific data type. The part “generator object” tells us the error concerns an illegal operation for the generator object.

The part “is not subscriptable” tells us we cannot access an element of the generator object using the subscript operator, which is square brackets [].

A subscriptable object is a container for other objects and implements the __getitem__() method. Examples of subscriptable objects include strings, lists, tuples, and dictionaries.

We can check if an object implements the __getitem__() method by listing its attributes with the dir function. Let’s call the dir function and pass a generator object and a str object to see their attributes.

# A generator function
def generator_func():

    yield 1

    yield 2

    yield 3

  
x = generator_func()

print(dir(x))

['__class__', '__del__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__iter__', '__le__', '__lt__', '__name__', '__ne__', '__new__', '__next__', '__qualname__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'close', 'gi_code', 'gi_frame', 'gi_running', 'gi_yieldfrom', 'send', 'throw']

We can see that __getitem__ is not present in the list of attributes for the generator object.

string = "Python"

print(dir(string))

['__add__', '__class__', '__contains__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__iter__', '__le__', '__len__', '__lt__', '__mod__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmod__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'capitalize', 'casefold', 'center', 'count', 'encode', 'endswith', 'expandtabs', 'find', 'format', 'format_map', 'index', 'isalnum', 'isalpha', 'isascii', 'isdecimal', 'isdigit', 'isidentifier', 'islower', 'isnumeric', 'isprintable', 'isspace', 'istitle', 'isupper', 'join', 'ljust', 'lower', 'lstrip', 'maketrans', 'partition', 'replace', 'rfind', 'rindex', 'rjust', 'rpartition', 'rsplit', 'rstrip', 'split', 'splitlines', 'startswith', 'strip', 'swapcase', 'title', 'translate', 'upper', 'zfill']

We can see that __getitem__ is present in the list of attributes for the str object.

If we want to check if a specific attribute belongs to an object, we can check for membership using the in operator.

# A generator function
def generator_func():

    yield 1

    yield 2

    yield 3
  
x = generator_func()

# Check type of object

print(type(x))

# Check membership of attribute

print('__getitem__' in dir(x))

<class 'generator'>
False

The variable x is an object of the generator class. We can see that __getitem__ is not an attribute of the generator class.

string = "Python"
print(type(string))
print('__getitem__' in dir(string))

<class 'str'>
True

We can see that __getitem__ is an attribute of the str class.

Example

Let’s look at an example of trying to access an element of a generator object using indexing. First, we will create the generator() function.

Generator functions allow us to declare a function that behaves like an iterator. We use a yield statement rather than a return statement in a generator function.

def generator_func():

    yield 2

    yield 3

    yield 8

Next, we will assign the generator object returned by the generator function to a variable,

x = generator_func()

Next, we will attempt to access the first item in the generator object using indexing syntax.

first_num = x[0]

print(first_num)

Let’s run the code to see what happens:

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Input In [41], in <cell line: 1>()
----> 1 first_num = x[0]
      2 print(first_num)

TypeError: 'generator' object is not subscriptable

The error occurs because the x variable is a generator object, which is an Iterator. Iterators generate values in order as requested by a for loop or by calling next(). We are trying to access values in the object as though it were a list or another subscriptable object.

Solution

We can solve this error by converting the generator object to a list using the built-in list() method.

Let’s look at the revised code:

def generator_func():

    yield 2

    yield 3

    yield 8

x = list(generator_func())

first_num = x[0]

print(first_num)

Let’s run the code to get the result:

2

The first item in the generator object is the number 2.

Summary

Congratulations on reading to the end of this tutorial!

For further reading on not subscriptable errors, go to the articles:

• How to Solve Python TypeError: ‘zip’ object is not subscriptable
• How to Solve Python TypeError: ‘dict_items’ object is not subscriptable
• How to Solve Python TypeError: ‘datetime.datetime’ object is not subscriptable

To learn more about Python for data science and machine learning, you can go to the online courses page on Python for the most comprehensive courses.

Have fun and happy researching!

I also get this error even after doing pip install networkx==1.11:

TypeError Traceback (most recent call last)
in ()
4 algo=tpe.suggest,
5 max_evals=2,
—-> 6 trials=trials)
7
8 print(best)

~/.envs/YM_py3.5/lib/python3.5/site-packages/hyperopt/fmin.py in fmin(fn, space, algo, max_evals, trials, rstate, allow_trials_fmin, pass_expr_memo_ctrl, catch_eval_exceptions, verbose, return_argmin)
305 verbose=verbose,
306 catch_eval_exceptions=catch_eval_exceptions,
—> 307 return_argmin=return_argmin,
308 )
309

~/.envs/YM_py3.5/lib/python3.5/site-packages/hyperopt/base.py in fmin(self, fn, space, algo, max_evals, rstate, verbose, pass_expr_memo_ctrl, catch_eval_exceptions, return_argmin)
633 pass_expr_memo_ctrl=pass_expr_memo_ctrl,
634 catch_eval_exceptions=catch_eval_exceptions,
—> 635 return_argmin=return_argmin)
636
637

~/.envs/YM_py3.5/lib/python3.5/site-packages/hyperopt/fmin.py in fmin(fn, space, algo, max_evals, trials, rstate, allow_trials_fmin, pass_expr_memo_ctrl, catch_eval_exceptions, verbose, return_argmin)
312
313 domain = base.Domain(fn, space,
—> 314 pass_expr_memo_ctrl=pass_expr_memo_ctrl)
315
316 rval = FMinIter(algo, domain, trials, max_evals=max_evals,

~/.envs/YM_py3.5/lib/python3.5/site-packages/hyperopt/base.py in init(self, fn, expr, workdir, pass_expr_memo_ctrl, name, loss_target)
784 before = pyll.dfs(self.expr)
785 # — raises exception if expr contains cycles
—> 786 pyll.toposort(self.expr)
787 vh = self.vh = VectorizeHelper(self.expr, self.s_new_ids)
788 # — raises exception if v_expr contains cycles

~/.envs/YM_py3.5/lib/python3.5/site-packages/hyperopt/pyll/base.py in toposort(expr)
713 G.add_edges_from([(n_in, node) for n_in in node.inputs()])
714 order = nx.topological_sort(G)
—> 715 assert order[-1] == expr
716 return order
717

TypeError: ‘generator’ object is not subscriptable