How to make a list from several nested lists

Question

I have a following nested list (All are in one list: One master list (Master) contains two list both of them contain by one list)

Master = \
["E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin [u'BGD_4_new_district', u'BGD_3_old_district', u'BGD_2_division', u'BGD_1_all', u'BGD_5_Upazilla', u'BGD_4_old_district', u'BGD_6_Union_court', u'BGD_6_Union', u'BD_exposed_coastal_area', u'BD_drought', u'BGD_1_River', u'BGD_1_River_detail', u'BD_international_bnd', u'BGD_1_River_1', u'BGD_7_Mauza', u'test', u'BGD_5_UpazillaAnno', u'BGD_4_new_districtAnno', u'BGD_4_new_districtAnno2']", 
 "E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BCAS_BD_Infrastructure    [u'BD_Health_Infrastructures_1', u'BD_Railway_Establishments_1', u'BGD_roads_1']"]

Now I want to make a list (as windows path) whose one element as below:(for the first list)

"E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\u'BGD_4_new_district"

again the included 'u' character for unicode and "'" after it also be removed so finally it be: In a elements in a List named "My_Path" are

"E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BGD_4_new_district" 
"E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BGD_3_old_district"
..........
..........
"E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BCAS_BD_Infrastructur\\BD_Health_Infrastructures_1"

@ Martijn Pieters My arcpy code is

import arcpy,os
p=[]
D=[]
admin="E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb"
arcpy.env.workspace =admin
datasetList = arcpy.ListDatasets("*", "Feature")
for dataset in datasetList:
d=str(dataset)
D.append(d)
dList = arcpy.ListTables() + arcpy.ListFeatureClasses() + arcpy.ListRasters()
for dataset in arcpy.ListDatasets():
    arcpy.env.workspace=os.path.join(admin,dataset)
    dList+=arcpy.ListDatasets()+arcpy.ListFeatureClasses()
    p.append(str(arcpy.env.workspace)+str(arcpy.ListFeatureClasses()))##--this makes list

You have one list with two strings. They are not nested lists. Part of the elements *look* like lists, but they are still just strings. You called `str()` on existing lists with unicode values. — Martijn Pieters, Jun 03 '13 at 08:23
Show us the code that build this list in the first place? I can help you fix these strings, but it'd be much, much easier and better if you didn't build these values in the first place. — Martijn Pieters, Jun 03 '13 at 08:24
arcpy does not produce output like this unless you call `str()` on something (or use string formatting). What is the code that produces `Master`? — Martijn Pieters, Jun 03 '13 at 09:03
Then please show that bit of code and I can help you avoid the EOF you are seeing with my attempt to repair the damage. Edit your question, add the lines of code that create the `Master` list. — Martijn Pieters, Jun 03 '13 at 09:10

Martijn Pieters · Accepted Answer · 2013-06-03T08:33:07.467

You have two strings with python lists embedded in them. They are not actual lists.

You can go back to making these into lists with unicode values with the ast.literal_eval() function. That feels like we are fixing a problem that was caused by other code, the better fix would be to not build these values like these in the first place.

from ast import literal_eval
import os.path

output = []
for entry in Master:
    base, lst = entry.split(None, 1)
    for name in literal_eval(lst):
        output.append(os.path.join(base, name))

This produces proper unicode paths (a good idea on Windows):

>>> output
[u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BGD_4_new_district', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BGD_3_old_district', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BGD_2_division', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BGD_1_all', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BGD_5_Upazilla', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BGD_4_old_district', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BGD_6_Union_court', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BGD_6_Union', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BD_exposed_coastal_area', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BD_drought', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BGD_1_River', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BGD_1_River_detail', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BD_international_bnd', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BGD_1_River_1', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BGD_7_Mauza', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\test', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BGD_5_UpazillaAnno', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BGD_4_new_districtAnno', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin\\BGD_4_new_districtAnno2', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BCAS_BD_Infrastructure\\BD_Health_Infrastructures_1', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BCAS_BD_Infrastructure\\BD_Railway_Establishments_1', u'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BCAS_BD_Infrastructure\\BGD_roads_1']
>>> print output[0]
E:\GIS_DOCUMENT\BCAS_Map\BCAS_All.gdb\BD_Admin\BGD_4_new_district

If you can, you want to change the original code to produce a dictionary instead, one that uses the base as keys, and a list of names as the value:

{'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BCAS_BD_Infrastructure': [u'BD_Health_Infrastructures_1',
                                                                      u'BD_Railway_Establishments_1',
                                                                      u'BGD_roads_1'],
 'E:\\GIS_DOCUMENT\\BCAS_Map\\BCAS_All.gdb\\BD_Admin': [u'BGD_4_new_district',
                                                        u'BGD_3_old_district',
                                                        u'BGD_2_division',
                                                        u'BGD_1_all',
                                                        u'BGD_5_Upazilla',
                                                        u'BGD_4_old_district',
                                                        u'BGD_6_Union_court',
                                                        u'BGD_6_Union',
                                                        u'BD_exposed_coastal_area',
                                                        u'BD_drought',
                                                        u'BGD_1_River',
                                                        u'BGD_1_River_detail',
                                                        u'BD_international_bnd',
                                                        u'BGD_1_River_1',
                                                        u'BGD_7_Mauza',
                                                        u'test',
                                                        u'BGD_5_UpazillaAnno',
                                                        u'BGD_4_new_districtAnno',
                                                        u'BGD_4_new_districtAnno2']}

what the heck! i m not able to use it; it comes with error of EOF — Learner, Jun 03 '13 at 09:09
@SharifulIslam: Then your actual data contains more than what `literal_eval()` can handle. — Martijn Pieters, Jun 03 '13 at 09:10

How to make a list from several nested lists

1 Answers1