TypeError can’t multiply sequence by non-int of type numpy.float64

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TypeError can’t multiply sequence by non-int of type numpy.float64 usually occurs when dealing with string types and trying to perform a different operation on them. Sometimes small and silly mistakes in Python can be very stressful and takes a lot of time and of them is the Can’t multiply sequence by non-int of type ‘numpy.float64’ error. In this tutorial, we will learn what is this error, why TypeError: can’t multiply sequence by non-int of type numpy.float64 error occurs, and how to solve such problems. Moreover, we will also learn how to interpret and understand errors in Python taking TypeError: can’t multiply sequence by non-int of type numpy.float64 error as an example:

Solve TypeError: Can’t multiply sequence by non-int of type numpy.float64 in Python

First, let us understand why we are getting this error. As you can see, the error starts saying TypeError which means the error occurs because of a conflict in the operation of data types.

Let us assume that we have a NumPy array containing elements of string type only. Now, let us say that we want to multiply the first element by any floating number. In such cases when we try to multiply the floating number with a string, we get TypeError: can’t multiply sequence by non-int of type float error as shown below:

# importing numpy module
import numpy as np

# creating a string array
string = np.array(["a","b","c"])

# multiplying an array with floating number
string[0]*5.1

Output:

TypeError-cant-multiply-sequence-by-non-int-of-type-float-error

As you can see, we get the error saying cannot multiply sequence by non-int of type float. Once you understand the cause of the problem, you can then easily find the solution to solve the issue:

Here are some of the following possible solutions to the given problem:

  • Using integer values
  • Rounding the floating points
  • Using math module
  • Using try-except block

Let us now go through each of the possible solutions.

Solution-1: Use integer instead of floating

As we know we are getting TypeError: Can’t multiply sequence by non-int of type numpy.float64 error because we are trying to perform an operation on string type using floating numbers which is not possible. We should use integer values rather than floating as shown below:

# importing numpy module
import numpy as np

# creating a string array
string = np.array(["a","b","c"])

# multiplying an array with floating number
string[0]*5

Output:

aaaaa

As you can see, we were able to perform the operation on the string values using an integer datatype.

Solution-2: Rounding the floating point

Sometimes, you might be using a variable or output of any other function to perform an operation on the array. By default, the output is a floating point. In such a case, you can simply round the floating point to nearby integer values:

# importing numpy module
import numpy as np

# creating a string array
string = np.array(["a","b","c"])

# multiplying an array with floating number
string[0]*round(5.1)

Output:

aaaaa

As you can see, we were able to get the output by simply using the round method. The round method converts the floating points to nearby integer values.

Solution-3: Using the math module
In the math module, we can use various techniques to convert floating points into integer values. For example the floor() and ceil() method. floor() method in Python returns the floor of x i.e., the largest integer not greater than x.

Let us first use the floor method to solve the issue:

# importing numpy module
import numpy as np
import math

# creating a string array
string = np.array(["a","b","c"])

# multiplying an array with floating number
string[0]*math.floor(5.1)

Output:

aaaaa

As you can see, we get desired output:

Another method is to use the ceil() method. The method ceil(x) in Python returns a ceiling value of x i.e., the smallest integer greater than or equal to x. Let us use the Ceil method to solve the issue:

# importing numpy module
import numpy as np
import math

# creating a string array
string = np.array(["a","b","c"])

# multiplying an array with floating number
string[0]*math.ceil(5.1)
aaaa

As you can see, the string was multiplied by 6 because the ceil method had returned 6 rather than 5. So, you have to keep in mind which function you are using.

Solution-4: Using try-except block

So far, we have learned how we can solve TypeError: can’t multiply sequence by non-int of type ‘numpy.float64’ using various methods. Another alternative is to handle such errors rather than solve them. In Python, the try-except blocks are used to handle any kind of error.

The code inside the try block will be executed and if there is an error, then instead of crashing the code, the except block will be executed to handle the error.

Let us take an example and see how we can use a try-except block to handle the given error:

# importing numpy module
import numpy as np

# creating a string array
string = np.array(["a","b","c"])

try:
    # multiplying an array with floating number
    string[0]*5.1
    
except:
    print("They given operation couldn't be performed")

Output:

They given operation couldn't be performed

As you can see, because of the error, the try block was not executed.

Understanding the can’t multiply sequence by non-int of type numpy.float64

Now let us try to understand the TypeError: can’t multiply sequence by non-int of type numpy.float64 error. In Python, usually, the errors have two main sections. The first part of the error is used to show the category of the error. In our example, the category of the error is TypeError which means there is something wrong with the data type.

The second part of the error gives more specific information and helps us to find the TypeError. For example, in our case, it clearly says that it cannot multiply the sequence with a non-int type which means we are somewhere in our program trying to multiply the sequence with non-integer values.

What is TypeError in Python and how to solve TypeError?

TypeError in Python is a type of exception that occurs when we tried to perform an operation on the wrong data type. In other words, this error shows that the given operation is invalid for the data type of the variable.

For example, if we have a string variable and a floating variable, and when we try to apply a multiplication operation, we will get a TypeError because the multiplication operation cannot be applied to a string variable.


# variables
var = 5.3
var1 ="Bashir"

# multiplication
var * var1
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
/tmp/ipykernel_311933/3047730713.py in <module>
      4 
      5 # multiplication
----> 6 var * var1

TypeError: can't multiply sequence by non-int of type 'float'

Notice that we got the TypeError because of an invalid operation between two different data-typed objects.

The simplest way to solve the TypeError is to use perform the operation on valid data types. You can check the data type of the variables using the type() function as shown below:

# variables
var = 5.3
var1 ="Bashir"

# printing
print(type(var))
print(type(var1))
<class 'float'>
<class 'str'>

As you can see, we got the data types of the variables.

Summary

In this short article, we learned how we can solve TypeError can’t multiply sequence by non-int of type ‘numpy.float64’ error using various methods. First, we discussed what this error means and how can solve it. Moreover, we discussed various methods to solve the TypeError can’t multiply sequence by non-int of type ‘numpy.float64’ error.

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