How to Fix ValueError Arrays Must All Be the Same Length in Python

We will introduce the causes and solutions of ValueError Arrays Must All Be The Same Length in Python with the help of examples.

the ValueError Arrays Must All Be The Same Length in Python

In this article, we’ll discuss the causes of getting ValueError Arrays Must All Be The Same Length while using data frames and how we can resolve them. Let’s take data frames into our perspective to understand the cause of the error message and then try to resolve it.

This error message occurs when we are trying to perform operations on arrays of different lengths in pandas’ data frames. Pandas data frames consist of columns, which act as arrays and contain the same number of values to make a data frame.

Suppose the columns are of different lengths; they will get through an error message and cannot combine into a single data frame. Let’s go through an example where we will recreate the error message by combining the data frames of different lengths.

Code Example:

# Python
import pandas as pd

df = pd.DataFrame({"Name": ["Husnain", "Alex", "Susan"], "Age": ["20", "25"]})
df["Data"] = df["Name"] + df["Age"]

Output:

From the above example, we tried to combine data frames of different lengths, and our code threw an error message. There is only one solution that can be used to make sure we never get this error message when we are trying to combine data frames.

We can eliminate this error message by ensuring that the data frames we are trying to combine are of equal length. We can easily do that using the len() function and if-else statement.

Let’s go through an example and try to resolve the error message.

Code Example:

# Python
import pandas as pd

df = pd.DataFrame({"Name": ["Husnain", "Alex", "Susan"], "Age": ["20", "25", "28"]})

if len(df["Name"]) == len(df["Age"]):
    df["Data"] = df["Name"] + df["Age"]
    print(df["Data"])

else:
    print("Columns have different lengths")

Output:

If the length of the data frames matches, our code will only try to combine them. If the length of the data frames is the same, only then will they be combined, and we will never get the error message.