# Add leading zeros to variable in list

## Question:

I tried to do some experimenting with variables in lists. Some of numbers wasn’t same length as original input.

For example:

Original: `[012, 125, 032]`

Result: `[12, 125, 32]`

How can I add leading zeros to equalise to original values?

I Have tried `zfill`

and `format`

but I don’t know how to loop it through.

## Answers:

First approach to keep leading zeros in a list of integers could be to use string formatting to convert the integers to strings with leading zeros. Here’s an example code snippet:

```
original_list = [12, 125, 32]
formatted_list = [f"{x:03d}" for x in original_list]
print(formatted_list)
```

Second approach could be using the `zfill`

function in the pandas library:

```
# importing pandas library
import pandas as pd
# converting the numeric to series to type pandas.Series
ol = pd.Series(original_list)
print(ol)
# to apply zfill function a series should be numeric so converting it to type object i.e string
out = ol.astype(str)
# https://pandas.pydata.org/docs/reference/api/pandas.Series.str.zfill.html
# calling zfill function to see changes i.e value 3 to make all string of equal size by adding leading zero
res = out.str.zfill(3)
```

Output:

```
0 12
1 125
2 32
dtype: int64
0 012
1 125
2 032
dtype: object
```