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Data Conversion?

P: 8
Hi,

I am responsible for a statistical analysis of a certain data for a research project. The program I want to run is matlab. So I want to make every cell to numbers but some exceptions with missing data.

Assume I have the following form of data. (I made up this.)

ID DATE X1 X2 X3 X4 X5 X6
1 18SEP2008 5 3 4 -1 -2 A
2 19SEP2008 9999 4 2 9 3 C
3 16SEP2008 2 0 9999 -8 -7 B

....



For X1 throught X3, 9999 means a missing data.
For X4 and X5, any negative number is a missing data.

I want to convert each date to the number representing days since Aug 10, 2008, for example.
For X1 through X6, all the missing data would be converted to NaN, or anything that can be recognized as missing by matlab.
For X6, A would be converted to 0 and B to 1, and C to 2. (the numbers don't matter as long as they are numbers distinguishing among different states A, B and so on.)

In the end, I want the data to be reorganized as:

ID DATE X1 X2 X3 X4 X5 X6
1 39 5 3 4 NaN NaN 0
2 40 NaN 4 2 9 3 2
3 37 2 0 NaN NaN NaN 1

....

(I may convert some data in matlab if it is more appropriate.)



I am new to Access and so please understand if my question is too basic.
If you can help me in whatever ways, please do that for me.


Thank you,

Joon
Sep 20 '08 #1
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7 Replies


ADezii
Expert 5K+
P: 8,619
Just subscribing, will come up with hopefully an approach within a day or two,
Sep 20 '08 #2

P: 69
It's not entirely clear what you need to do in detail, but as a starting point you should know that Access stores dates as numbers with the zero point being 31 Dec 1899. So, to get the number of days since your chosen start date, you simply need to subtract that date from each imported date. If you are doing this in a query, you will need to enclose the start date in hash signs - '#'. If you are trying to use Visual Basic, you should probably use the VBA function
CDate(mm/dd/yyyy) to define your start date. The help files have a lot of guidance about how Access deals with dates. I don't know where you are, but you should probably be careful about the precise format of date you use. Because Access is US software, it is generally more comfortable with mm/dd/yy and you may very well use dd/mm/yy or even yy/mm/dd.
Sep 21 '08 #3

ADezii
Expert 5K+
P: 8,619
  1. Let's make the simple assumption that your test data is stored in a Table named tblTestData. Original idea isn't it! (LOL).
  2. Create the following Table named tblFinalResults whose purpose is indicated by its Name. It will hold the converted Values suitable for MetLab. Define the following Fields:
    • [ID] - {LONG}
    • [DATE] - {INTEGER}
    • X1 - {TEXT}
    • X2 - {TEXT}
    • X3 - {TEXT}
    • X4 - {TEXT}
    • X5 - {TEXT}
    • X6 - {TEXT}
  3. Copy and Paste the following 'Public' Function into a Standard Code Module. Herein lies the logic which will perform the conversion based on your Specifications, then append the data to the tblFinalResults.
    Expand|Select|Wrap|Line Numbers
    1. Public Function fConvertDataToMatLab()
    2. Dim MyDB As DAO.Database
    3. Dim rstTestData As DAO.Recordset
    4. Dim rstFinal As DAO.Recordset
    5. Dim lngID As Long
    6. Dim dteDate As Date
    7. Dim intCounter_1 As Integer
    8. Dim intDateDiff As Integer
    9. Dim varX1, varX2, varX3, varX4, varX5, varX6    'Variants
    10. Const dteBaseDate As Date = #8/10/2008#     'change if so desired
    11.  
    12. Set MyDB = CurrentDb
    13. Set rstTestData = MyDB.OpenRecordset("tblTestData", dbOpenForwardOnly)
    14. Set rstFinal = MyDB.OpenRecordset("tblFinalResults", dbOpenDynaset)
    15.  
    16. 'DELETE any pre-existing results
    17. CurrentDb.Execute "Delete * From tblFinalResults", dbFailOnError
    18.  
    19. With rstTestData
    20.   Do While Not .EOF
    21.     lngID = ![ID]
    22.     'DDMMMYYYY is not a valid Date Format, but DD-MMM-YYYY is. We must convert to this
    23.     'Format so that we can calculate the differential between this Data and a Base Date
    24.     '(dteBaseDate), 8/10/2008 in this case
    25.     dteDate = CDate(Left$(![Date], 2) & "-" & Mid$(![Date], 3, 3) & "-" & Right$(![Date], 4))
    26.     intDateDiff = DateDiff("d", dteBaseDate, dteDate)
    27.       If ![X1] = 9999 Then      '9999 indicates missing data, convert to NaN
    28.         varX1 = "NaN"
    29.       Else
    30.         varX1 = ![X1]           'maintain existing value
    31.       End If
    32.       If ![X2] = 9999 Then      '9999 indicates missing data, convert to NaN
    33.         varX2 = "NaN"
    34.       Else
    35.         varX2 = ![X2]           'maintain existing value
    36.       End If
    37.       If ![X3] = 9999 Then      '9999 indicates missing data, convert to NaN
    38.         varX3 = "NaN"
    39.       Else
    40.         varX3 = ![X3]           'maintain existing value
    41.       End If
    42.       If ![X4] < 0 Then         'any Value < 0 is considered to be missing data,
    43.         varX4 = "NaN"           'convert to NaN
    44.       Else
    45.         varX4 = ![X4]           'maintain existing value
    46.       End If
    47.       If ![X5] < 0 Then         'any Value < 0 is considered to be missing data,
    48.         varX5 = "NaN"           'convert to NaN
    49.       Else
    50.         varX5 = ![X5]           'maintain existing value
    51.       End If
    52.         varX6 = Asc(![X6]) - 65     'single characters A thru Z converted to
    53.       rstFinal.AddNew               '0 to 25 respectively
    54.         rstFinal![ID] = ![ID]
    55.         rstFinal![Date] = intDateDiff
    56.         rstFinal![X1] = varX1
    57.         rstFinal![X2] = varX2
    58.         rstFinal![X3] = varX3
    59.         rstFinal![X4] = varX4
    60.         rstFinal![X5] = varX5
    61.         rstFinal![X6] = varX6
    62.       rstFinal.Update
    63.       .MoveNext
    64.   Loop
    65. End With
    66.  
    67. rstFinal.Close
    68. Set rstFinal = Nothing
    69. rstTestData.Close
    70. Set rstTestData = Nothing
    71.  
    72. 'Finally, let's see the results!
    73. DoCmd.OpenTable "tblFinalResults", acViewNormal, acReadOnly
    74. DoCmd.Maximize
    75. End Function
  4. Call the Function in any manner you so desire, I'll post the simplest:
    Expand|Select|Wrap|Line Numbers
    1. Call fConvertDataToMatLab
  5. OUTPUT (tblFinalResults):
    Expand|Select|Wrap|Line Numbers
    1. ID    DATE    X1    X2    X3    X4    X5    X6
    2. 1    39    5    3    4    NaN    NaN    0
    3. 2    40    NaN    4    2    9    3    2
    4. 3    37    2    0    NaN    NaN    NaN    1
  6. If you actually performed all the previous steps, shame on you! Just download the Test Database used for this Thread, I've made it available as an Attachment.
  7. Any questions, please feel free to ask. Either myself, or someone else, will be happy to answer them for you.
Sep 21 '08 #4

P: 8
Thank you, Adezii.
I really appreciate your help.

Joon
Sep 22 '08 #5

ADezii
Expert 5K+
P: 8,619
Thank you, Adezii.
I really appreciate your help.

Joon
You are quite welcome, Joon.
Sep 22 '08 #6

Megalog
Expert 100+
P: 378
Nice conversion!

But Joon should know that for the X6 conversion, it is case sensitive. 'A' will not result in the same number as 'a'. This would only be an issue I suppose if it's all being keyed in by hand, in which case a validation could be ran.
Sep 22 '08 #7

ADezii
Expert 5K+
P: 8,619
Nice conversion!

But Joon should know that for the X6 conversion, it is case sensitive. 'A' will not result in the same number as 'a'. This would only be an issue I suppose if it's all being keyed in by hand, in which case a validation could be ran.
Good point Megalog. I made the assumption, perhaps erroneously, that the data existing in the pre-converted Format would be in a rigid, consistent state. To allow for this possibility, all that would be needed is a simple code adjustment:
Expand|Select|Wrap|Line Numbers
  1. varX6 = Asc(UCase$(![X6])) - 65
P.S. - The OP seemed to indicate that this value itself was not critical, only that numeric values generated from it would be 'Unique' for each Character and be able to be Grouped.
Sep 22 '08 #8

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