ENVI二次开发时调用决策树的方法

决策树方法是一种常用的分类方法，由于ENVI没有提供自带的决策树调用接口，本文介绍如何通过安装决策树sav文件在ENVI二次开发中调用决策树接口。

通过百度网盘下载sav文件及示例代码。

链接：https://pan.baidu.com/s/1P4EQ-KjGpw9chspfRs4krw 
提取码：envi 

1. 将batch_decision_tree.sav拷贝到：C:\Program Files\Harris\ENVI5x\classic\save_add；


2. 修改示例代码中，tree_file，ndvi_file及slope_file文件路径，运行示例代码；

    

   pro test_batch_dtree
compile_opt idl2

ENVI, /restore_base_save_files
ENVI_BATCH_INIT
;Supply existing decision tree text file
tree_file = 'D:\decision_tree_ndvi_slope.txt'
;Open relevant image files
ndvi_file = 'C:\Program Files\Harris\ENVI56\classic\data\bhtmref.img'
slope_file = 'C:\Program Files\Harris\ENVI56\classic\data\bhdemsub.img'
envi_open_file, ndvi_file, r_fid = ndvi_fid
envi_open_file, slope_file, r_fid = slope_fid
;Build arrays of tree variables, input file ids, and band positions
;Order is crucial. The first file id and band position array are tied to the first variable, and so on....
;Band positions for each file, as listed in the decision tree text file under "file pos", are 1-based. Input to this routine is zero-based, so
;be sure to account for that. Example: file pos = 4,3 -> pos = [3,2]. Because the number of bands can vary for each variable, they
;must be stored in a structure variable.
var_names = ['ndvi','slope']
in_fids = [ndvi_fid, slope_fid]
pos_struct = {ndvi:[3,2], slope:[0]}
;Specify an output filename
out_file = 'D:\batch_dt_test.img'
;Specify which input image to use as the base, along with the spatial dimensions to operate on
base_fid = ndvi_fid
envi_file_query, base_fid, dims=base_dims
;Specify an interpolation method for resizing the imagery involved. Required, even if not used in the decision process.
;Options are:
;
;0 - Nearest Neighbor
;1 - Bilinear
;2 - Cubic Convolution
;
;0 is always the safest option. If interpolation isn't required, the specified value is ignored.
interp = 2
;Call the batch routine. Result should show up in the ABL
batch_decision_tree, tree_file=tree_file, in_fids=in_fids, pos_struct=pos_struct, var_names=var_names, out_file=out_file, $
base_fid=base_fid, base_dims=base_dims, interp=interp, r_fid=r_fid
end