python - 将点转换为线 Geopandas

Question

您好，我正在尝试将 X 和 Y 坐标列表转换为直线。我想通过 groupby ID 和时间来映射这些数据。只要我 grouby 一列，我的代码就可以成功执行，但是两列是我遇到错误的地方。我引用了这个question .

这是一些示例数据:

ID  X           Y           Hour
1   -87.78976   41.97658    16
1   -87.66991   41.92355    16
1   -87.59887   41.708447   17
2   -87.73956   41.876827   16
2   -87.68161   41.79886    16
2   -87.5999    41.7083     16
3   -87.59918   41.708485   17
3   -87.59857   41.708393   17
3   -87.64391   41.675133   17

这是我的代码:

df = pd.read_csv("snow_gps.csv", sep=';')

#zip the coordinates into a point object and convert to a GeoData Frame
geometry = [Point(xy) for xy in zip(df.X, df.Y)]
geo_df = GeoDataFrame(df, geometry=geometry)

# aggregate these points with the GrouBy
geo_df = geo_df.groupby(['track_seg_point_id', 'Hour'])['geometry'].apply(lambda x: LineString(x.tolist()))
geo_df = GeoDataFrame(geo_df, geometry='geometry')

这是错误:ValueError: LineStrings must have at least 2 coordinate tuples

这是我想要得到的最终结果:

ID          Hour     geometry
1           16       LINESTRING (-87.78976 41.97658, -87.66991 41.9... 
1           17       LINESTRING (-87.78964000000001 41.976634999999... 
1           18       LINESTRING (-87.78958 41.97663499999999, -87.6... 
2           16       LINESTRING (-87.78958 41.976612, -87.669785 41... 
2           17       LINESTRING (-87.78958 41.976624, -87.66978 41.... 
3           16       LINESTRING (-87.78958 41.97666, -87.6695199999... 
3           17       LINESTRING (-87.78954 41.976665, -87.66927 41.... 

请就如何对多个参数进行分组提出任何建议或想法。

Answer 1

你的代码很好，问题是你的数据。

你可以看到，如果按 ID 和 Hour 分组，则只有 1 个 ID 为 1，小时为 17 的点。一个 LineString 必须由 1 个或多个点组成(必须至少有2 个坐标元组)。我在您的示例数据中添加了另一点:

ID   X          Y           Hour
1   -87.78976   41.97658    16
1   -87.66991   41.92355    16
1   -87.59887   41.708447   17
1   -87.48234   41.677342   17
2   -87.73956   41.876827   16
2   -87.68161   41.79886    16
2   -87.5999    41.7083     16
3   -87.59918   41.708485   17
3   -87.59857   41.708393   17
3   -87.64391   41.675133   17

正如您在下面看到的，下面的代码几乎与您的相同:

import pandas as pd
import geopandas as gpd
from shapely.geometry import Point, LineString, shape

df = pd.read_csv("snow_gps.csv", sep='\s*,\s*')

#zip the coordinates into a point object and convert to a GeoData Frame
geometry = [Point(xy) for xy in zip(df.X, df.Y)]
geo_df = gpd.GeoDataFrame(df, geometry=geometry)

geo_df2 = geo_df.groupby(['ID', 'Hour'])['geometry'].apply(lambda x: LineString(x.tolist()))
geo_df2 = gpd.GeoDataFrame(geo_df2, geometry='geometry')