在 ogr 或 geopandas python 的 shapefile 中创建 FID 列答案

【问题标题】：create a FID column in shapefile in ogr or geopandas python在 ogr 或 geopandas python 的 shapefile 中创建 FID 列
【发布时间】：2021-05-14 10:19:17
【问题描述】：

我需要 shapefile 中 FID 列的信息。加载 shapefile 时，不知何故该列未“显示”。我需要该栏的信息，因为我需要说如下内容：

fid	id	label
1	1	forest
2	1	forest
3	2	water
4	2	water
5	3	urban

我需要知道哪些fids 属于ID 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

【问题讨论】：

标签： python shapefile geopandas osgeo

【解决方案1】：

好的...读了一点之后，我发现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

你知道更好的方法吗？

【讨论】：