Append to Array Fails

[Jeff]

The Script that I will post will show 2 different results Function - def Report_Results_Fail(): -- Fails Function - def Report_Results_Ok(): -- is OK

I am trying to understand why the first fails

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def Processes_Last_Runs_Blanks_Clear(v_User_List):     v_Blanks_Clear = [] ; v_Blanks_Clear.append("--||--")     for i in range(len(v_User_List)):         v_This = "-"#+" " * v_User_Len         #v_This = v_This[0:v_User_Len]         v_Blanks_Clear.append(v_This)     return v_Blanks_Clear   def Active_User_List():     # Read from file so array looks like this     v_Users_Active = []     v_Users_Active.append("Jeff")     v_Users_Active.append("Kenny")     v_Users_Active.append("Lenny")     v_Users_Active.append("Manny")     v_Users_Active.append("Nanny")     return v_Users_Active   def Report_Results_Fail():     v_Users_Active = Active_User_List()     v_Blanks = Processes_Last_Runs_Blanks_Clear(v_Users_Active)     v_Report = []     v_Report.append(v_Blanks)     v_Report[0][0] = "Process"     v_Report[0][1] = "Users"     for i in range(5):         if i == len(v_Report):             v_Report.append(v_Blanks)         v_Report[i][1] = str(i)     for i in range(len(v_Report)):         print i,v_Report[i]   def Report_Results_Ok():     v_Users_Active = Active_User_List()     v_Report = []     v_Report.append(Processes_Last_Runs_Blanks_Clear(v_Users_Active))     v_Report[0][0] = "Process"     v_Report[0][1] = "Users"     for i in range(5):         if i == len(v_Report):             v_Report.append(Processes_Last_Runs_Blanks_Clear(v_Users_Active))         v_Report[i][1] = str(i)     for i in range(len(v_Report)):         print i,v_Report[i]   print "Running on Imac High Sierra 10.13.6 - Python Version  2.7.10" print "Report_Results_Fail()" Report_Results_Fail() print "Report_Results_Ok()" Report_Results_Ok()

>>>> Result
Running on Imac High Sierra 10.13.6 - Python Version 2.7.10

Report_Results_Fail()

Output:
0 ['Process', '4', '-', '-', '-', '-']

1 ['Process', '4', '-', '-', '-', '-']

2 ['Process', '4', '-', '-', '-', '-']

3 ['Process', '4', '-', '-', '-', '-']

4 ['Process', '4', '-', '-', '-', '-']

Report_Results_Ok()

Output:
0 ['Process', '0', '-', '-', '-', '-']

1 ['--||--', '1', '-', '-', '-', '-']

2 ['--||--', '2', '-', '-', '-', '-']

3 ['--||--', '3', '-', '-', '-', '-']

4 ['--||--', '4', '-', '-', '-', '-']

[ichabod801]

The reason they are giving different outputs if v_Blanks, which is a list you append to v_Report. On line 24, you change the copy you appended to v_Report, but lists don't copy unless you do it explicitly. Instead, you get a pointer to the old list. You when you change the version in v_Report, you change the original v_Blanks as well. On line 29, you change the latest v_Blanks that you appended to v_Report. But again, all the v_Blanks your are appending are just references to the same v_Blanks, so the output looks like you changed every copy the same way, because they're all the same list.

To explicitly copy a list, do a whole list slice: v_Blanks[:]. Note this is a "shallow" copy, any lists or other mutable objects in v_Blanks will be copied as references.

Also, you should switch to Python 3. At the end of the year support for 2.7 will stop.