# Pandas notes

## Apply a function with multiple arguments to pandas DataFrame columns - using DataFrame.apply()

`DataFrame.apply()` applies a function along an axis of the DataFrame. 

Following is the syntax:

```python
DataFrame.apply(func, axis=0, raw=False, result_type=None, args=(), **kwds)
```

{% hint style="info" %}
Reference: <https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.apply.html>
{% endhint %}

Use `args=(param1, param2, )` parameter in `DataFrame.apply()` method to pass additional arguments to a function.

It takes function parameters in a tuple. The first argument is series by default so you don't need to pass it.

**Example:** Convert an ISO date/DateTime stamp (*`2021-04-12T07:21:00.345344`*) to standard  \
(`2021-04-10 07:21:00.345344`) format.

{% code title="apply\_test.py" %}

```python
import pandas as pd

def date_to(row, col_name):
''' Function to convert an ISO date format to standard date format'''
        row[col_name] = pd.to_datetime(row[col_name]).strftime('%Y-%m-%d %H:%M%:%S.%f')
        #row[col_name] = pd.to_datetime(row[col_name]).strftime('%Y-%m-%d %H:%M%:%S.%f')[:-3]
        return row[col_name]


sample_dates = {
            "Date": [
                "2021-04-12T07:21:00.345344",
                "2015-10-19T07:18:00.234234",
                "2018-11-19T07:15:00.423423",
            ],
            "AnotherDate": [
                "2018-12-22T07:21:00.963344",
                "2019-08-19T07:18:00.887234",
                "2020-03-20T07:15:00.765423",
            ]
        }
        
df = pd.DataFrame(s2)
# df['Date'] = df.apply(date_to, axis=1) :apply function without paramter.
df["Date"] = df.apply(date_to, args=("Date",), axis=1) # apply function with paramter.
df["AnontherDate"] = df.apply(date_to, args=("AnontherDate",), axis=1)
```

{% endcode %}

#### Outpu&#x74;**:**

```python
                         Date                AnotherDate
0  2021-04-12 07:21:00.345344  2018-12-22 07:21:00.963344
1  2015-10-19 07:18:00.234234  2019-08-19 07:18:00.887234
2  2018-11-19 07:15:00.423423  2020-03-20 07:15:00.765423
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://stalwartcoder.gitbook.io/abhishek-notes/master.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.