If you have a Pandas dataframe like the following (if you already have a DataFrame based on a query result, you can use that):
import pandas as pd data = [['tom', 10], ['nick', 15], ['juli', 14]] df = pd.DataFrame(data, columns = ['Name', 'Age'])
Basic Pandas DataFrame
I wanted a dictionary where I could provide the name (“tom”, “nick”, or “juli”) and receive their age as the result. To convert your DataFrame to a dictionary like this, you’d use the following command:
Now that you have a dictionary, you can do lookups or whatever else you want. Make sure you take note above that the first parameter uses “values” where the second one doesn’t. If you use values in the second parameter, or you just try to use the “.todict()” function on the DataFrame directly, without converting it to a series first as above, you can end up with Dictionaries with an entry for each column, or dictionaries that contain dictionaries, or a number of other things that don’t work.
Short and to the point – this took me about an hour to find the answer to and hopefully you find it before losing that much time!
While developing a Windows Mobile device application on two different computers, I thought I’d installed SQL Server Compact Edition 3.5 SP2 on both of them, but ran into some version difference issues. In researching it, I couldn’t find good information about the different versions of the System.Data.SqlCompactCe DLL, so thought some future developers might enjoy what I found out, all in one place.
The Problem:
After checking the project into source control on one computer and fetching it on the other, I’d see a broken reference to System.Data.SqlServerCe:
Missing reference to System.Data.SqlServerCe
And I received the following message (and about 100 errors – one for every reference to the namespace in my code) when I attempted to compile:
Warning 10 Could not resolve this reference. Could not locate the assembly “System.Data.SqlServerCe, Version=3.5.1.0, Culture=neutral, PublicKeyToken=3be235df1c8d2ad3, processorArchitecture=MSIL”. Check to make sure the assembly exists on disk. If this reference is required by your code, you may get compilation errors.
If I dropped the reference, re-added it on my second computer (BTW – only one version was listed in my .NET reference list on both machines) and checked it back in, then I’d get the same situation on my first computer with the following error message:
Warning 10 Could not resolve this reference. Could not locate the assembly “System.Data.SqlServerCe, Version=3.5.0.0, Culture=neutral, PublicKeyToken=3be235df1c8d2ad3, processorArchitecture=MSIL”. Check to make sure the assembly exists on disk. If this reference is required by your code, you may get compilation errors.
The Research:
I had a DLL version mismatch – a general problem when you’ve got multiple computers you’re developing something on, since you have to ensure the same versions and packages are installed on each. However, searching for details on the different versions of this DLL in the wild wasn’t fruitful – did I have SQL Compact 3.5 RTM installed (3.5.0.0)? If I’d installed v3.5 SP2, why was it shown as 3.5.1.0 (shouldn’t it be 3.5.2.0?) on one machine, but as 3.5.0.0 the other? To top that off, both versions (v3.5.0.0 and v3.5.1.0) were in my GAC as MSIL – what?
It turns out that when you add a reference to this DLL in a Compact Framework project, Visual Studio is using the following version (depending on whether you’re on an x86 or x64 machine):
x86: C:\Program Files\Microsoft SQL Server Compact Edition\v3.5\Devices\System.Data.SqlServerCe.dll x64: C:\Program Files (x86)\Microsoft SQL Server Compact Edition\v3.5\Devices\System.Data.SqlServerCe.dll
There, I found my issue – that file version was a different version on each machine (3.5.5692.0 on one and 3.5.8080.0 on the other). To find out why, I had to dig into the registry, where I found all kinds of version information about the SQL Server Compact Edition components I’d installed, the DLL version, and the service pack levels:
x86 or x64 components HKLM\SOFTWARE\Microsoft\Microsoft SQL Server Compact Edition\v3.5\ENU
or if you want to see x86 components installed on your x64 machine: HKLM\SOFTWARE\Wow6432Node\Microsoft\Microsoft SQL Server Compact Edition\v3.5\ENU
There, you’ll find a combination of “Version” and “ServicePackLevel” entries for every SQL CE component you have installed, and it will shed some light. Here are the version numbers I found (for the various components):
So how did I end up with the SP1 version installed on one machine, but not on the other? Since I’d installed SQL Compact SP2 on both machines, I was baffled. As it turns out, Visual Studio 2008 RTM deploys SQL Compact 3.5 RTM (3.5.5386.0), and applying Visual Studio 2008 SP1 patches that to the SP1 version (3.5.5692.0) – notice the VSToolsVersion/VSToolsServicePackLevel values in the registry location above, which reflect your current service pack level of Visual Studio 2008.
The Solution:
While I’d installed VS 2008 SP1 on both machines, I’d installed the actual SQL Compact 3.5 SP2 for Windows Mobile (EDIT 2016-10-31: This link has been updated to the current location for this download) package on only one machine and not the other – this left the DLL on one machine patched to SP1 (courtesy of Visual Studio) and the other machine with a fully-patched SP2 DLL (courtesy of the actual SP2 Windows Mobile installer).
I confirmed this by running the SP2 for Windows Mobile installer, and it patched my DLL right up to the full SP2 version – problem resolved, and the project now opens up on both workstations with no need for any DLL reference swapping.
The Moral:
Honestly, a bit embarrassing and a pretty amateur move where some vigilance could have saved me quite a bit of aggrivation.
ENSURE YOU’RE DEPLOYING ALL THE SAME PACKAGES ON ALL DEVELOPMENT MACHINES! JUST BECAUSE SOMETHING ALREADY EXISTS ON ONE MACHINE, DON’T ASSUME IT’S THE SAME VERSION!
