如何解决在 ogr 或 geopandas python
我需要来自 shapefile 的 FID 列的信息。不知何故,当您加载 shapefile 时,该列不会“显示”。我需要该列的信息,因为我需要说:
fid | id | 标签 |
---|---|---|
1 | 1 | 森林 |
2 | 1 | 森林 |
3 | 2 | 水 |
4 | 2 | 水 |
5 | 3 | 城市 |
我需要知道哪些 fids 属于 ids X、Y、Z 等。我在 geopandas 中尝试了以下内容。使用 osgeo 的 geopandas 或 OGR 是否有更有效的方法?谢谢
import os
import geopandas as gpd
import numpy as np
from osgeo import ogr
# open the training data
train_cl_fn = os.path.join(src,"train.shp")
# read the column "id" that already exists. This id column says that feature X belongs to id Y
X_train_G = gpd.read_file(train_cl_fn)
class_ids = X_train_G["id"].unique()
print('class ids: ',class_ids)
# I create an empty array for the fids
class_fids = np.array([])
print('class labels: ',class_fids)
# add "fidl" column,using "id" and the empty array
# FID and fid are the same,therefore "fidl"
X_train_G['fidl'] = X_train_G['id'].map(dict(zip(class_ids,class_fids)))
print(X_train_G.head())
# export: rewrite file
X_train_G.to_file(os.path.join(src,"train.shp"))
# open the SAME file again,this time in ogr
train_cl_fn = os.path.join(src,"train.shp")
driver = ogr.GetDriverByName('ESRI Shapefile')
train_ds = driver.Open(train_cl_fn,1) # 0 means read-only. 1 means writeable.
layer = train_ds.GetLayer()
for Ft in layer:
ThisID = int(Ft.GetFID())
#print('id is {}'.format(ThisID))
Ft.SetField('fidl',ThisID) # Write the FID to the fidl field
layer.SetFeature(Ft) # update the feature
dataSource = None # save/rewrite file with fid info in the fidl column
解决方法
好的……阅读了一些之后,我找到了一种更有效的方法。
import os
from osgeo import ogr
src = "C:/path/"
#### Read SHP and create X_train_x segments array ####
# open training data
train_cl_fn = os.path.join(src,"train.shp")
driver = ogr.GetDriverByName('ESRI Shapefile')
train_ds = driver.Open(train_cl_fn,1) # 0 means read-only. 1 means writeable.
layer = train_ds.GetLayer()
fieldDefn = ogr.FieldDefn('fidl',ogr.OFTReal)
fieldDefn.SetWidth(14)
fieldDefn.SetPrecision(6)
layer.CreateField(fieldDefn)
for Ft in layer:
ThisID = int(Ft.GetFID())
#print('id is {}'.format(ThisID))
Ft.SetField('fidl',ThisID) # Write the FID to the fidl field
layer.SetFeature(Ft) # update the feature
dataSource = None
你知道一种更好的方法吗?
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