https://github.com/abhishekmishragithub/gitbook-notes

Random notes
https://github.com/abhishekmishragithub/gitbook-notes

notes programming python system-design

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Random notes

• Host: GitHub
• URL: https://github.com/abhishekmishragithub/gitbook-notes
• Owner: abhishekmishragithub
• Created: 2024-02-01T07:22:16.000Z (11 months ago)
• Default Branch: main
• Last Pushed: 2024-04-02T11:10:55.000Z (9 months ago)
• Last Synced: 2024-04-02T13:05:21.102Z (9 months ago)
• Topics: notes, programming, python, system-design
• Homepage: https://stalwartcoder.gitbook.io/abhishek-notes/
• Size: 22.5 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
---

description: Some notes/code snippet related to pandas operations.

---

# 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](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 %}

#### Output**:**

```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

```