Ошибка valueerror shape mismatch objects cannot be broadcast to a single shape

Valueerror: shape mismatch: objects cannot be broadcast to a single shape error might occur when you perform an arithmetic operation on differently shaped variables. Moreover, another reason can be an attempt to plot the vectors having different lengths. Don’t worry if the causes have confused you even more because this article will explain to you the same in detail. Read more to dive into the details of the causes and get the best solution to eliminate the stated error.

The above error is occurring because you are trying to compute differently shaped variables. Also, the given value error might appear when you plot the vectors that don’t have similar lengths. Please read the cause descriptions for more clarity.

– Performing Arithmetic Operation on Differently Shaped Variables

The line of code that attempts to calculate differently shaped variables will throw the error mentioned above. It is because the given variables won’t be compatible with each other. Consequently, they won’t be able to produce an output irrespective of the type of arithmetic operator being used.

The issue was once noticed while using SciPy’s pearsonr(x,y) method. The erroneous code inside the said method looked like this: res = n*(np.add.reduce(xm*ym)).

So, here the issue seemed to be related to the x and y variables. The different shapes of x and y don’t allow the multiplication of both the variables resulting in the above error.

– Plotting Vectors of Different Lengths

Are you getting the above error while working with matplotlib and numpy libraries? Well, then a possible reason can be the different lengths of the vectors to be plotted. It is because the matplotlib doesn’t know about the procedure of plotting such vectors.

The example erroneous code can be seen here:

import matplotlib.pyplot as plt
import numpy as np
vector1 = np.arange(9)
vector2 = np.arange(8)
plt.bar(vector1, vector2)

How To Fix the Above Error?

You can fix the value error stated in the title by adjusting the shapes of the variables and the lengths of the vectors accordingly. So, once you’ve figured out the erroneous code in your program, opt for any of the given solutions to resolve the error:

– Adjust the Shapes of Variables To Remove ValueError: Shape Mismatch: Objects Cannot Be Broadcast To a Single Shape

You should adjust the shapes of the variables before performing any arithmetic operation on the same. Indeed, it is important to ensure that the variables are compatible with each other. Well, the error might go away even if you manipulate the variables on the same line that performs an arithmetic operation on the same. Here, you only need to ensure that the manipulation is carried out before the calculation.

– Align the Lengths of the Vectors To Be Plotted

Did your coding mistake resemble the second cause shared above? If yes, then the solution is super-easy and simplest. You only have to adjust the lengths of the vectors to make them the same, not even one number up or down. Consequently, you’ll see the error go away and the vectors will be plotted perfectly.

Solving Your Query

Here is a common question that relates to the above error:

– Why Does the Error Targeting Mismatched Shapes Pops Up While Using str.len()?

The stated error might occur when you improperly specify a condition that compares the lengths of two or more variables by using str.len(). Here, you should look for any extra parenthesis and remove them. Also, wrapping each sub-condition inside individual parenthesis can make the code work for you and eliminate the error.

Here is an example code that works:

(str1.str.len() != str2.str.len())
((str1.str.len() != 7) & (str2.str.len() == 10))

Conclusion

You have now understood enough about the value error that targetted the shapes of the variables and indirectly, the lengths of the vectors as well. Please see the below list to have a quick revision of the solutions discussed above:

• The error is occurring because you are trying to compute differently shaped variables.
• Adjusting the shapes of the variables before using them in a mathematical expression can help you in resolving the error.
• You should ensure that the lengths of the vectors are the same before plotting them to solve the above error.

Interestingly, even the error statement will seem clear to you after reading this article. So, get back to your program, look for the incompatible variables or vectors, and correct them to proceed further.

I am working in python3 and I want to obtain a stacked barchart plot, showing three different variables on 5 different columns.
My code works fine if I do not add the ‘bottom parameter’ in plt.bar (but I need to, in order for the stacks to appear in the correct order):

import numpy as np
import matplotlib as plt

columns=['a','b','c','d','e']
pos = np.arange(5)
var_one=[40348,53544,144895,34778,14322,53546,33623,76290,53546]
var_two=[15790,20409,87224,22085,6940,27099,17575,41862,27099]
var_three=[692,3254,6645,1237,469,872,569,3172,872]

plt.bar(pos,var_one,color='green',edgecolor='green')
plt.bar(pos,var_two,color='purple',edgecolor='purple')
plt.bar(pos,var_three,color='yellow',edgecolor='yellow')
plt.xticks(pos, columns)
plt.show()

However, once I add the bottom parameter in bar.plot (as shown below):

import numpy as np
import matplotlib as plt

columns=['a','b','c','d','e']
pos = np.arange(5)
var_one=[40348,53544,144895,34778,14322,53546,33623,76290,53546]
var_two=[15790,20409,87224,22085,6940,27099,17575,41862,27099]
var_three=[692,3254,6645,1237,469,872,569,3172,872]

plt.bar(pos,var_one,color='green',edgecolor='green')
plt.bar(pos,var_two,color='purple',edgecolor='purple',bottom=var_one)
plt.bar(pos,var_three,color='yellow',edgecolor='yellow',bottom=var_one+var_two)
plt.xticks(pos, columns)
plt.show()

the code triggers the error

ValueError: shape mismatch: objects cannot be broadcast to a single shape

How could I fix it?