使用 Panel Select Widget 从下拉菜单中选择后，从文件路径交互式创建 DataFrame

Question

我想要一个带面板的 Select 小部件，我可以在其中 select 来自字典的 ID。 ID 是键，值是存储表格数据的 geojson 文件的文件路径。在我交互式地选择一个 id 之后，应该加载数据框。我的问题是它只在我第一次选择一个值时起作用。如果我尝试 select 另一个，数据框将不会更新。 pandas 是否有可能在我选择新 ID 后更新 read_file 功能？

# Import modules
from glob import glob
import geopandas as gpd
import panel as pn
# Initializes the pyviz notebook extension to allow plotting with bokeh and enable comms
pn.extension()

# Store all filepaths within a list
filespaths = ['C://Users/USER/Desktop/Master_Irrigation/03_GIS/ground_trouth/sentinel_ismn_data\1018_15.15537_48.1521.geojson',
 'C://Users/USER/Desktop/Master_Irrigation/03_GIS/ground_trouth/sentinel_ismn_data\1026_15.15472_48.15053.geojson']

# Create Station id linked with filepath
ids = [x.split('\')[-1].split('_')[0] for x in filespaths]
#Create dict with Ids as key and filepaths as value
files = dict(zip(ids,filespaths ))

# Widget to select station id, widget.value stores filepath
id_selector = pn.widgets.Select(name='ISMN Station ID', options=files)

# Load file into GeoPandas DataFrame
gdf = gpd.read_file(id_selector.value)
id_selector

编辑：我知道一种方法是将所有数据加载到一个 DataFrame

gpd = gpd.tools.util.pd.concat(map(gpd.read_file, paths), ignore_index=True)

但是对于数百个包含数千行的文件，这会导致性能问题。

Answer 1

从根本上说，您需要考虑您的范式。您正在使用基于事件的范例，因此需要回调来响应您的事件（从下拉列表中选择的文件）
我没有使用过面板并且无法使用回调。因此，鉴于您的运行时环境是 jupyter（基于评论）

ipwidgets

以此响应事件并使用选定的文件加载 gdf。通过使用 glob() 查找 geojson 文件

import ipywidgets as widgets
from pathlib import Path
from glob import glob
import geopandas as gpd

# Store all filepaths within a list
# filespaths = ['C://Users/USER/Desktop/Master_Irrigation/03_GIS/ground_trouth/sentinel_ismn_data\1018_15.15537_48.1521.geojson',
#  'C://Users/USER/Desktop/Master_Irrigation/03_GIS/ground_trouth/sentinel_ismn_data\1026_15.15472_48.15053.geojson']
# well my filesystem is different,  get some geojson files
filespaths = list(set(Path.cwd().glob("**/*.geojson")) -  set(Path.cwd().glob(".ipynb_checkpoints/*.geojson")))

# Create Station id linked with filepath
# ids = [x.split('\')[-1].split('_')[0] for x in filespaths]
# my filenames don't contain any underscores ...
ids = list(range(len(filespaths)))
#Create dict with Ids as key and filepaths as value
files = dict(zip(ids,filespaths ))

gdf = None

# useful for debug....
out = widgets.Output(layout={"border": "1px solid black"})
out.append_stdout("Output appended with append_stdout\n")

# use ipwidgets instead
id_selector = widgets.Dropdown(
    options=[(k,v) for k,v in files.items()],
    description='ISMN Station ID:',
    disabled=False,
)

# the key a callback on value change....
@out.capture()
def changed(v):
    global gdf
    if v['type'] == 'change':
        print(v["new"])
        gdf = gpd.read_file(str(v["new"]))
id_selector.observe(changed, names="value")

widgets.VBox([id_selector, out])

使用 Panel Select Widget 从下拉菜单中选择后，从文件路径交互式创建 DataFrame

Create DataFrame from filepath interactive after choosing from Drop Down menu with Panel Select Widget

python

panel

widget

pandas

geopandas