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# Pandas cannot merge a series without a name
- URL: https://datascientyst.com/pandas-cannot-merge-a-series-without-a-name/
- Published: 2023-02-08T14:47:56.000Z
- Updated: 2023-02-08T14:47:56.000Z
- Author: John D K
- Tags: Pandas Error

In this short guide, I'll show you how to solve Pandas error:

> ValueError: Cannot merge a Series without a name

The error appears when we try to merge two Pandas series without a name. To solve the error we can set name to the series either by:

**(1) Rename series for the merge**

```python
pd.merge(s1.rename('old'), s2.rename('new'), left_index=True, right_index=True)

```

**(2) Set name for Series**

```python
s1.name = 'Series 1'

```

## ValueError: Cannot merge a Series without a name

To reproduce the error we will create two Pandas Series and try to merge them:

```python
import pandas as pd

s1 = pd.Series([1, 2, 3])
s2 = pd.Series([4, 5, 6])

result = pd.merge(s1, s2, left_index=True, right_index=True)

```

This results into Pandas error:

```
ValueError: Cannot merge a Series without a name

```

## Fix - ValueError: Cannot merge a Series without a name

To fix this error we can apply two solutions:

### Fix set new name

Set permanent name for the Pandas series:

```python
import pandas as pd

s1 = pd.Series([1, 2, 3])
s1.name = 'old'

s2 = pd.Series([4, 5, 6])
s2.name = 'new'

result = pd.merge(s1, s2, left_index=True, right_index=True)
result

```

This will change the Series:

```
0	1
1	2
2	3
Name: old, dtype: int64

```

The result is new DataFrame:

|   | old | new |
| - | --- | --- |
| 0 | 1   | 4   |
| 1 | 2   | 5   |
| 2 | 3   | 6   |

### Temporary rename series

We can solve the error without changing the series by using method `rename()`:

```python
import pandas as pd

s1 = pd.Series([1, 2, 3])
s2 = pd.Series([4, 5, 6])

result = pd.merge(s1.rename('old'), s2.rename('new'), left_index=True, right_index=True)
result

```

At the end the series is the same:

```
0	1
1	2
2	3
dtype: int64

```