Use numpy.concatenate(list1 , list2) or numpy.append()

Look into the thread at Concatenate a NumPy array to another NumPy array.

Answer from Arpita Biswas on Stack Overflow
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Statology
statology.org › home › how to fix: ‘numpy.ndarray’ object has no attribute ‘append’
How to Fix: 'numpy.ndarray' object has no attribute 'append'
August 4, 2021 - To fix this error, we simply need to use np.append() instead: import numpy as np #define NumPy array x = np.array([1, 4, 4, 6, 7, 12, 13, 16, 19, 22, 23]) #append the value '25' to end of NumPy array x = np.append(x, 25) #view updated array ...
Discussions

Week 2 Exercise 6 "'numpy.ndarray' object has no attribute 'append'"
Any idea why I am getting this error? Is costs not a numpy array? Exercise 5 runs properly but then I get this error after exercise 6 when using the line “costs.append(cost)”. Thanks for any help! More on community.deeplearning.ai
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March 8, 2022
AttributeError: 'numpy.ndarray' object has no attribute 'extend'
I got an error saying that 'numpy.ndarray' object(which is the schedule in the following code) has no attribute 'extend'. More on github.com
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April 11, 2016
AttributeError: 'numpy.ndarray' object has no attribute 'numpy'
@ptrblck, Hi! I’m trying to visualize the adversarial images generated by this script: https://pytorch.org/tutorials/beginner/fgsm_tutorial.html This tutorial is used for the mnist data. Now I want to use for other data which is trained using the inception_v1 architecture, below is the gist ... More on discuss.pytorch.org
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April 9, 2019
AttributeError with numpy array in NEAT algorithm for OpenAI Gym integration
The main problem happens when I try to process the observation data from the game environment. Here’s the error I get: AttributeError: 'numpy.ndarray' object has no attribute 'append' Here’s my current implementation: import retro import numpy as np import neat import cv2 game_env = ... More on community.latenode.com
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June 28, 2025
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GeeksforGeeks
geeksforgeeks.org › python › how-to-fix-numpy-ndarray-object-has-no-attribute-append
How to Fix: ‘numpy.ndarray’ object has no attribute ‘append’ - GeeksforGeeks
November 28, 2021 - As in the output, we can see that initially, the NumPy array had 4 items (1, 2, 3, 4). After appending 5 to the list, it is reflected in the NumPy array. This is so because here the append function is used on NumPy and not on NumPy array object (numpy.ndarray).
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Career Karma
careerkarma.com › blog › python › python attributeerror: ‘numpy.ndarray’ object has no attribute ‘append’ solution
Python AttributeError: 'numpy.ndarray' object has no attribute 'append' Solution
December 1, 2023 - The AttributeError: ‘numpy.ndarray’ object has no attribute ‘append’ error is caused by using the append() method to add an item to a NumPy array.
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DeepLearning.AI
community.deeplearning.ai › course q&a › deep learning specialization › neural networks and deep learning
Week 2 Exercise 6 "'numpy.ndarray' object has no attribute 'append'" - Neural Networks and Deep Learning - DeepLearning.AI
March 8, 2022 - Any idea why I am getting this error? Is costs not a numpy array? Exercise 5 runs properly but then I get this error after exercise 6 when using the line “costs.append(cost)”. Thanks for any help!
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Quora
quora.com › Why-do-I-get-numpy-ndarray-object-has-no-attribute-append-error
Why do I get “numpy.ndarray object has no attribute append error”? - Quora
Summary The AttributeError is simply because ndarray has no append method. Choose the appropriate container or numpy function for your use case: list for frequent appends, preallocation for efficiency, or np.append/np.concatenate when copying ...
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NumPy
numpy.org › doc › 2.1 › reference › generated › numpy.ndarray.html
numpy.ndarray — NumPy v2.1 Manual
The parameters given here refer to a low-level method (ndarray(…)) for instantiating an array. For more information, refer to the numpy module and examine the methods and attributes of an array. ... Shape of created array. ... Any object that can be interpreted as a numpy data type.
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Brainly
brainly.com › computers and technology › high school › how can you fix the attributeerror: 'numpy.ndarray' object has no attribute 'append'?
[FREE] How can you fix the AttributeError: 'numpy.ndarray' object has no attribute 'append'? - brainly.com
November 19, 2023 - If you need to add elements to a NumPy array, you can use the 'numpy.append' function instead. The 'AttributeError: 'numpy.ndarray' object has no attribute 'append'' error occurs when you try to use the 'append' method on a NumPy array.
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Edureka Community
edureka.co › home › community › categories › python › attributeerror numpy ndarray object has no...
AttributeError numpy ndarray object has no attribute append | Edureka Community
May 5, 2020 - Hi Guys, I am trying to append new dataset in my array using append function, but It is showing ... attribute 'append' How can I solve this error?
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GitHub
github.com › santoshphilip › eppy › issues › 96
AttributeError: 'numpy.ndarray' object has no attribute 'extend' · Issue #96 · santoshphilip/eppy
April 11, 2016 - Hi all, I got an error saying that 'numpy.ndarray' object(which is the schedule in the following code) has no attribute 'extend'. for i in range(7): for schedulename in range(len(ScheduleCompact)): if ScheduleCompact[schedulename].Name =...
Author   nancynanxiaodan
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sebhastian
sebhastian.com › numpyndarray-object-has-no-attribute-append
How to fix AttributeError: 'numpy.ndarray' object has no attribute 'append' | sebhastian
May 11, 2023 - AttributeError: 'numpy.ndarray' object has no attribute 'append' This error occurs when you attempt to add an element to the NumPy array object using the append() method. This tutorial will show you an example that causes this error and how I fix it in practice.
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Elements of AI
community.elementsofai.com › c › building-ai › exercise-21-advanced
Exercise 21 - Advanced | Elements of AI
January 15, 2025 - I encountered an error while working in the environment for exercise 21 on the advanced level. The error message is: AttributeError: 'numpy.ndarray' object has no attribute 'append' on line -26 This error suggests that there may be hidden code in the...
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Latenode
community.latenode.com › other questions › openai
AttributeError with numpy array in NEAT algorithm for OpenAI Gym integration - OpenAI - Latenode Official Community
June 28, 2025 - The main problem happens when I try to process the observation data from the game environment. Here’s the error I get: AttributeError: 'numpy.ndarray' object has no attribute 'append' Here’s my current implementation: import retro import numpy as np import neat import cv2 game_env = ...
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Delft Stack
delftstack.com › home › howto › python › numpy ndarray object has no attribute append
How to Fix the AttributeError: 'numpy.ndarray' Object Has No Attribute 'Append' in Python | Delft Stack
February 2, 2024 - the AttributeError: 'numpy.ndarray' ... NumPy doesn’t have the append() method for the array; instead, we need to use the append() method from NumPy....
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Itsourcecode
itsourcecode.com › home › (solved) numpy.ndarray object has no attribute append
(SOLVED) numpy.ndarray object has no attribute append
March 21, 2023 - The numpy.ndarray object has no attribute append is an error message that occurs when you are trying to call the append method on the array numpy, and does not have any attribute.
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Physics Forums
physicsforums.com › other sciences › programming and computer science
Appending a dictionary whose keys contain np arrays • Physics Forums
August 15, 2022 - The discussion revolves around issues encountered while trying to append a new numpy array to an existing key in a dictionary that stores numpy arrays. The user attempts to use the `setdefault` method with a list as the default value, leading to confusion and errors. The first error arises from trying to use `np.append` incorrectly, as 'np' is not an attribute of numpy arrays.