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How to Fix: ValueError: setting an array element with a sequence

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  • Last Updated : 10 Feb, 2022

In this article, we will discuss how to fix ValueError: setting array element with a sequence using Python.

Error which we basically encounter when we using Numpy library is ValueError: setting array element with a sequence. We face this error basically when we creating array or dealing with numpy.array. 

This error occurred because of when numpy.array creating array with given value but the data-type of value is not same as data-type provided to numpy. 

Steps needed to prevent this error:

  • Easiest way to fix this problem is to use the data-type which support all type of data-type.
  • Second way to fix this problem is to match the default data-type of array and assigning value.

Method 1: Using common data-type

Example : Program to show error code:

Python




# In this program we are demonstrating how different
# Data-type can cause value error
 
import numpy
 
# Creating multi-dimension array
array1 = [1, 2, 4, [5, [6, 7]]]
 
# Data type of array element
Data_type = int
 
# This cause Value error
np_array = numpy.array(array1, dtype=Data_type)
 
print(np_array)


Output:

 File “C:\Users\computers\Downloads\he.py”, line 13, in <module>

 np_array = numpy.array(array1,dtype=Data_type);

ValueError: setting an array element with a sequence.

We can fix this error if we provide the data type  which support all data-type to the element of array:

Syntax: 

numpy.array( Array ,dtype = Common_DataType );

Example: Fixed code

Python




# In this program we fix problem by different data-type
 
import numpy
 
# Creating multi-dimension array
array1 = [1, 2, 4, [5, [6, 7]]]
 
# Object Data type is accept all data-type
Data_type = object
 
# Now we fix the error
np_array = numpy.array(array1, dtype=Data_type)
 
print(np_array)


Output:

[1 2 4 list([5, [6, 7]])]

Method 2:  By matching default data-type of value and Array

Example: Program to show error

Python




# In this program we are demonstrating how mismatch
# of data-type can cause value error
 
import numpy
 
# Creating array
array1 = ["Geeks", "For"]
 
# Default Data type of Array
Data_type = str
 
 
np_array = numpy.array(array1, dtype=Data_type)
# This cause error
np_array[1] = ["for", "Geeks"]
print(np_array)


Output:

File “C:\Users\computers\Downloads\he.py”, line 15, in <module>

np_array[1] = [“for”,”Geeks”];

ValueError: setting an array element with a sequence

Here we have seen that this error is cause because we are assigning array as a element to array which accept string data-type. we can fix this error by matching the data-type of value and array and then assign it as element of array.

Syntax: 

if np_array.dtype == type( Variable ):
      expression;

Example: Fixed code

Python




# In this program we fix error by mismatch
# of data-type
 
import numpy
 
# Creating array
array1 = ["Geeks", "For"]
 
# Default Data type of Array
Data_type = str
 
 
np_array = numpy.array(array1, dtype=Data_type)
 
Variable = ["for", "Geeks"]
 
# First we match the data-type
if np_array.dtype == type(Variable):
    np_array[1] = Variable
else:
    print("Variable value is not the type of numpy array")
print(np_array)


Output:

Variable value is not the type of numpy array
['Geeks' 'For']

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