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docs: Dataframe docs update #693

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title: "Dataframe"
---

**writer framework places the dataframe at the core of the application**. This is a great way for modeling a complex and massive data system.
it offers components as `dataframe` to manipulate dataframes. These components allow you to visualize and interact with dataframes.
## DataFrames

| compatibility | dataframe |
|--------------------|---------------------------------------|
| `pandas.DataFrame` | x |
| `polar.DataFrame` | x |
| `list of records` | x (with `EditableDataframe`) |
If your application needs to present data as a table, it should use a **DataFrame**. DataFrames provide a simple way to present data in a grid format, require only a couple of lines of code to set up, and provide an interface that users expect from modern data applications.

## Use a dataframe
![DataFrame showing a table of popular ice cream flavors](/framework/images/dataframe.png)

**a dataframe is simply added to the state**. A component like `dataframe` will be able to display it.
DataFrames built-in features that users expect, such as headers that can be clicked to change the sort order and resizable columns...

```python
import pandas
import writer as wf
![DataFrame with arrows pointing to the re-sort and resizing features](/framework/images/dataframe_resort_resize.png)

wf.init_state({
'mydf': pandas.DataFrame({'a': [1, 2, 3], 'b': [4, 5, 6]})
})
```
...and with the simple change of a parameter, you can enable features such as the Search field, which lets the user find the data they’re looking for (or filter out unwanted data), and the Download button, which downloads the data currently being displayed as a .csv file:

![DataFrame with arrows pointing to the Search field and Download button](/framework/images/dataframe_search_download.png)

You can find the full list of DataFrame properties and fields on the [_DataFrame_ component page](/components/dataframe).

### “DataFrame” has multiple meanings

**Writer Framework has two objects with the name _DataFrame_:**
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Can we add an intro sentence here to help people understand what they're trying to accomplish with dataframes?


1. **UI DataFrame:** In Writer Framework's UI, "DataFrame" refers to a **_user interface component_** that displays data in rows and columns in a way similar to a spreadsheet or SQL table.
2. **Code Dataframe:** In code that you write for a Writer Framework application, `DataFrame` refers to a **_data structure_** that stores data in rows and columns in a way similar to a spreadsheet or SQL table.

To present a data table in Writer Framework, you create a `DataFrame` data structure in your code and then bind it to a UI Dataframe.


## Displaying a static DataFrame
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Can we please briefly discuss the options in the DataFrame component (e.g. sorting, downloading, searching) and link to the component documentation.


A static DataFrame is one whose content does not change. The user can change its sort order, but the data within the DataFrame remains constant.

<Steps>
<Step title="Create a DataFrame data structure">
Writer Framework supports both [pandas](https://pandas.pydata.org/) and [Polars](https://pola.rs/) `DataFrame` data structures. Create a `DataFrame`, assign its value to a variable, then assign make that variable a value in the `state` dictionary:

## Prepare a dataframe for editing
<CodeGroup>
```python pandas
import writer as wf
import pandas as pd

**writer provides `EditableDataframe` as a helper to facilitate manipulation**. it makes it easier to write event handlers such as adding a line,
deleting it or modifying a value, etc...
data = [
{"rank": 1, "flavor": "Vanilla", "favorite": 0.11},
{"rank": 2, "flavor": "Chocolate", "favorite": 0.1},
{"rank": 3, "flavor": "Cookies and cream", "favorite": 0.07},
{"rank": 4, "flavor": "Strawberry", "favorite": 0.06},
{"rank": 5, "flavor": "Chocolate chip", "favorite": 0.02},
]
df = pd.DataFrame(data)

wf.init_state({
"mydf": df
})
```

```python Polars
import writer as wf
import polars as pl

data = [
{"rank": 1, "flavor": "Vanilla", "favorite": 0.11},
{"rank": 2, "flavor": "Chocolate", "favorite": 0.1},
{"rank": 3, "flavor": "Cookies and cream", "favorite": 0.07},
{"rank": 4, "flavor": "Strawberry", "favorite": 0.06},
{"rank": 5, "flavor": "Chocolate chip", "favorite": 0.02},
]
df = pl.DataFrame(data)

wf.init_state({
"mydf": df
})
```
</CodeGroup>

The call to `wf.init_state()` adds the `DataFrame` to the application's `state` variable as the value of the `mydf` key.
</Step>
<Step title="Add a DataFrame component to the UI and bind it to the DataFrame data structure">
Add a DataFrame UI component to the user interface, then set its **Data** property to `@{`_dataframe_key_`}`, where _dataframe_key_ is the `state` variable key whose value refers to the `DataFrame` data structure.
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The underscores at the front and end of _dataframe_key_ add italics and break the code formatting, I'd remove them.


In the case of this example, `mydf` is the `state` variable key referring to the `DataFrame`, so set the **Data** property to `@{mydf}`.

![DataFrame for static table example with properties panel open](/framework/images/dataframe_static_table_1.png)
</Step>
</Steps>


## Displaying an editable DataFrame

A editable DataFrame is one whose content can change. Like static DataFrames, editable DataFrames use the **DataFrame** UI component. Unlike static tables, the DataFrame UI component is bound to an instance of `EditableDataFrame`, a class provided by the Writer library. Changes to a `EditableDataFrame` object will be immediately reflected in the DataFrame UI component that it is bound to.

<Steps>
<Step title="Create an EditableDataFrame data structure">
An `EditableDataFrame` object can be instantiated from any of the following:

1. A pandas `DataFrame`
2. A Polars `DataFrame`
3. A list of dictionaries

<CodeGroup>
```python pandas
import writer as wf
import pandas as pd

data = [
{"rank": 1, "flavor": "Vanilla", "favorite": 0.11},
{"rank": 2, "flavor": "Chocolate", "favorite": 0.1},
{"rank": 3, "flavor": "Cookies and cream", "favorite": 0.07},
{"rank": 4, "flavor": "Strawberry", "favorite": 0.06},
{"rank": 5, "flavor": "Chocolate chip", "favorite": 0.02},
]
df = pd.DataFrame(data)

wf.init_state({
"mydf": wf.EditableDataFrame(df)
})
```

```python Polars
import writer as wf
import polars as pl

data = [
{"rank": 1, "flavor": "Vanilla", "favorite": 0.11},
{"rank": 2, "flavor": "Chocolate", "favorite": 0.1},
{"rank": 3, "flavor": "Cookies and cream", "favorite": 0.07},
{"rank": 4, "flavor": "Strawberry", "favorite": 0.06},
{"rank": 5, "flavor": "Chocolate chip", "favorite": 0.02},
]
df = pl.DataFrame(data)

wf.init_state({
"mydf": wf.EditableDataFrame(df)
})
```

```python List of dictionaries
import writer as wf

data = [
{"rank": 1, "flavor": "Vanilla", "favorite": 0.11},
{"rank": 2, "flavor": "Chocolate", "favorite": 0.1},
{"rank": 3, "flavor": "Cookies and cream", "favorite": 0.07},
{"rank": 4, "flavor": "Strawberry", "favorite": 0.06},
{"rank": 5, "flavor": "Chocolate chip", "favorite": 0.02},
]

wf.init_state({
"mydf": wf.EditableDataFrame(data)
})
```
</CodeGroup>

The call to `wf.init_state()` adds the `DataFrame` to the application's `state` variable as the value of the `mydf` key.
</Step>
<Step title="Add a DataFrame component to the UI and bind it to the DataFrame data structure">
Add a **DataFrame** component to the user interface, then set its **Data** property to `@{`_dataframe_key_`}`, where _dataframe_key_ is the `state` variable key whose value refers to the `DataFrame` data structure.

In the case of this example, `mydf` is the `state` variable key referring to the `DataFrame`, so set the **Data** property to `@{mydf}`.

![DataFrame for dynamic table example with properties panel open](/framework/images/dataframe_dynamic_table_1.png)
</Step>
</Steps>

## Updating an editable DataFrame

Editable DataFrames are updated by updating the `EditableDataFrame` object they are bound to, which is done using `EditableDataFrame`'s methods.

### `record_add`: Add a new row

`record_add()` adds a new row to an `EditableDataFrame`. It takes a dictionary with the following structure...

```python
import pandas
import writer as wf
{"record": new_row}
```

df = pandas.DataFrame({'a': [1, 2, 3], 'b': [4, 5, 6]})
...where `new_row` is a dictionary containing the data for the row to be added.

wf.init_state({
'mydf': wf.EditableDataframe(df)
})
In the code example above, you would add a new row to the DataFrame with the following code:

```python
state["mydf"].record_add({"record": {"rank": 6, "flavor": "Birthday cake", "favorite": 0.01}})
```

### Handle events from a dataframe editor
### `record`: Read the contents of a row

`record()` returns a row in an `EditableDataFrame`. It takes an integer specifying the index of the row.

**The dataframe component emits events when an action is performed**. You must subscribe to events to integrate changes to the state of the application.
In the code example above, you would retrieve the record at row 1 with the following code:

```python
import pandas
import writer as wf
record = state["mydf"].record(1)
```

df = pandas.DataFrame({'a': [1, 2, 3], 'b': [4, 5, 6]})
wf.init_state({
'mydf': wf.EditableDataframe(df)
})
### `record_update`: Change an existing row

# Subscribe this event handler to the `wf-dataframe-add` event
def on_record_add(state, payload):
payload['record']['sales'] = 0 # default value inside the dataframe
state['mydf'].record_add(payload)
`record_update()` replaces an existing row in an `EditableDataFrame` with a new one. It takes a dictionary with the following structure...

```python
{
"record_index": index,
"record": row_to_update
}
```

# Subscribe this event handler to the `wf-dataframe-update` event
def on_record_change(state, payload):
state['mydf'].record_update(payload)
...where `index` is an integer specifying which row should be updated and `row_to_update` is a dictionary containing the updated row data.

In the code example above, you would update the row at index 0 with the following code:

# Subscribe this event handler to the `wf-dataframe-action` event
def on_record_action(state, payload):
"""
This event corresponds to a quick action in the drop-down menu to the left of the dataframe.
"""
record_index = payload['record_index']
if payload['action'] == 'remove':
state['mydf'].record_remove(payload)
if payload['action'] == 'open':
state['record'] = state['df'].record(record_index) # dict representation of record
```python
state["mydf"].record_update({
"record_index": 0,
"record": {"rank": 6, "flavor": "Bubble gum", "favorite": 0.08}
})
```

### Datastructures supported by `EditableDataframe`
### `record_remove`: Delete an existing row

`EditableDataframe` can be used with a panda dataframe, a polar dataframe and list of records.
`record_remove()` removes an existing row from an `EditableDataFrame`. It takes a dictionary with the following structure...

```python
import pandas
import polars
{"record_index": index}
```

import writer as wf
...where `index` is an integer specifying which row should be deleted.

panda_df = pandas.DataFrame({'a': [1, 2, 3], 'b': [4, 5, 6]})
polars_df = polars.DataFrame({'a': [1, 2, 3], 'b': [4, 5, 6]})
list_of_records = [{'a': 1, 'b': 4}, {'a': 2, 'b': 5}, {'a': 3, 'b': 6}]
In the code example above, you would delete the row at index 2 with the following code:

wf.init_state({
'mypandas': wf.EditableDataframe(panda_df),
'mypolars': wf.EditableDataframe(polars_df),
'mylistofrecords': wf.EditableDataframe(list_of_records)
})
```python
state["mydf"].record_remove({"record_index": 2})
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Seems like this is missing a conclusion or something to wrap this up and tell the user where to go next

```


## Enabling additional features

The DataFrame component has these “always-on” features:

1. **Sorting:** Clicking a column header sorts the entire DataFrame based on that column's values. The first click sorts that DataFrame in ascending order, a second click changes it to descending order, and a third click restores the DataFrame to its original sort order.
2. **Column resizing:** Click and drag the dividing line on the right edge of a column header to adjust its width.

DataFrames have other features that you need to activate, which are listed below.

### Search field

To enable the Search field, select the DataFrame, open the Component settings panel, and set **Enable search** to **yes**.

![Enabling the Search field in a DataFrame](/framework/images/dataframe_enable_search.png)

### Download button

To enable the Download button, select the DataFrame, open the Component settings panel, and set **Enable download** to **yes**.

![Enabling the Download button in a DataFrame](/framework/images/dataframe_enable_download.png)

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