Only Size-1 Arrays Can Be Converted To Python Scalars

Welcome to Codingcompiler. In this blog post, we are going to explain why this TypeError: Only Size-1 Arrays Can Be Converted To Python Scalars occur and how to fix Only Size-1 Arrays Can Be Converted To Python Scalars in different ways.

Why Only Size-1 Arrays Can Be Converted To Python Scalars Occur?

Here we’ll explain this Python type error with an example.

Example Python Code:

import numpy as np
import matplotlib.pyplot as plt

def f(x):
    return np.int(x)

x = np.arange(1, 15.1, 0.1)
plt.plot(x, f(x))
plt.show()

The above Python example gives the “TypeError: only length-1 arrays can be converted to Python scalars“.

How To Fix TypeError: Only Size-1 Arrays Can Be Converted To Python Scalars

Let’s discuss how to fix this Python TypeError.

Solution – 1

The error “only length-1 arrays can be converted to Python scalars” is raised when the function expects a single value but you pass an array instead.

If you look at the call signature of np.int, you’ll see that it accepts a single value, not an array. In general, if you want to apply a function that accepts a single element to every element in an array, you can use np.vectorize:

Here is the code example to fix the error:

import numpy as np
import matplotlib.pyplot as plt

def f(x):
    return np.int(x)
f2 = np.vectorize(f)
x = np.arange(1, 15.1, 0.1)
plt.plot(x, f2(x))
plt.show()

Error explanation:

You can skip the definition of f(x) and just pass np.int to the vectorize function: f2 = np.vectorize(np.int).

Note: That np.vectorize is just a convenience function and basically a for loop. That will be inefficient over large arrays. Whenever you have the possibility, use truly vectorized functions or methods (like astype(int).

Solution – 2

Use: x.astype(int)

Here is the reference.

This error reference: Stackoverflow.

We hope that you got your answer for the error “only length-1 arrays can be converted to Python scalars“. If anything to discuss, please drop your comment in the below comment box.

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