Python Error: valueerror: setting an array element with a sequence

Error messages are a given in almost any kind of programming. When you throw a whole new function library into the mix, you will have even more errors than you did before- that can be said of Python’s Numpy library. Numpy is a widely used scientific computing package for Python, and a requirement if you want to do any serious scientific work with the language.

What does it mean?

The error message reading valueerror: setting an array element with a sequence is a relatively common error that pops up when you use an np array out of the Numpy library. If the Numpy array element is set up incorrectly, if the Numpy array element has a different length, or you are using a multi dimensional array, you may have this issue when using a certain Python function. This could include different length of string values, or a multi dimensional array with some other data type error or value error. Generally, it is caused by a problem with different data types being used in your Python code, usually with some type of object you have created.

Why does it occur?

This valueerror happens in an np array when the sequence elements are not consistent, or the type of element does not match another element or object, such as these example code snippets:

  • np.array([[7, 4], [2, 4, 9]])
  • np.array([3.1, 2.5, “Tony”], dtype=float)

Each example input listed here gives the error message when used in your python code, though they vary slightly- the first is because it is a multidimensional array with varying element levels, and the second example is because it attempts to put string values into a number object.

How do I fix it?

The solution to the valueerror: setting an array element with a sequence involves adjusting the scalar, vector, or other object that is causing the error message. It is likely a simple mistake in the matrix or array function, so simply fix those mistakes to avoid the error:

  • np.array([[7, 4], [2, 4, 9]]) – Produces the error message
  • np.array([[7, 4, 0], [2, 4, 9]]) – Does not produce the error message
  • np.array([3.1, 2.5, “Tony”], dtype=float) – Produces the error message
  • np.array([3.1, 2.5, “Tony”], dtype=object) – Does not produce the error message

It can be as simple as adding a zero to fix the array, or simply changing the data type of the object to avoid this error message. It may seem confusing, but this problem has a simple solution, requiring cleaning up the mistakes in your python code to make everything run smoothly.

Python Error: valueerror: setting an array element with a sequence
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