In our Utopian imaginations all the data would have been standardized and shareable across systems and people. But alas, the reality is totally different. We seldom get data in the format / way we desire it to be. In other words, the ingredients are all there, but for us to prepare the dinner, you must pre-process them.
Often this pre-processing or cleaning up the data takes quite an amount of time it self leaving very little to do the actual work. That is when you can use excel’s powerful data cleaning techniques to handle the situations.
One common problem with corporate data is incorrectly formatted phone numbers. Most of us are used to a standard 10 digit phone number format like 123-123-1234 or (123) 123 1234, but when you get that customer data, very few phone numbers in it are formatted like above. Instead you might see phone numbers like 1231231234, 12312 31234, (123)123-1234 etc.
It is not really difficult to clean up the phone numbers if we know before hand how they are formatted. For eg. you can easily convert a phone number like 1231231234 to 123-123-1234 using excel text formatting functions like =TEXT(1231231234,"000-000-0000"). But it is a rare case in which we have control over the incoming format and quickly you will have to use a slew of format / text processing functions to clean up the data.
To simplify the whole thing, I have written a small VBA UDF (User Defined Function) which you can add to your excel add-ins list and use to clean up virtually any phone number format to standard phone number.
Function cleanPhoneNumber(thisNumber As String) As String
' this function aspires to clean any phone number format
' to standard format (+9999) 999-999-9999 or 999-999-9999
' works with almost all phone number formats stored in text
Dim retNumber As String
For i = 1 To Len(thisNumber)
If Asc(Mid(thisNumber, i, 1)) >= Asc("0") And Asc(Mid(thisNumber, i, 1)) <= Asc("9") Then
retNumber = retNumber + Mid(thisNumber, i, 1)
End If
Next
If Len(retNumber) > 10 Then
' format for country code as well
cleanPhoneNumber = Format(retNumber, "(+#) 000-000-0000")
Else
cleanPhoneNumber = Format(retNumber, "000-000-0000")
End If
End Function
The above function is pretty straight forward and simple. It scans the input text for any numeric ASCII codes and saves them to another text field. Once the scanning is complete the function will format the final number to 999-999-9999 format if the number has 10 or less digits, otherwise to (+9999) 999-999-9999 format (with country code).
Like this? Learn these other data cleaning / processing tips:
Handling spelling mistakes in your data
Splitting text using excel formulas
Generating initials from names using excel
Adding a range of cells using Concat()
8 Responses to “Pivot Tables from large data-sets – 5 examples”
Do you have links to any sites that can provide free, large, test data sets. Both large in diversity and large in total number of rows.
Good question Ron. I suggest checking out kaggle.com, data.world or create your own with randbetween(). You can also get a complex business data-set from Microsoft Power BI website. It is contoso retail data.
Hi Chandoo,
I work with large data sets all the time (80-200MB files with 100Ks of rows and 20-40 columns) and I've taken a few steps to reduce the size (20-60MB) so they can better shared and work more quickly. These steps include: creating custom calculations in the pivot instead of having additional data columns, deleting the data tab and saving as an xlsb. I've even tried indexmatch instead of vlookup--although I'm not sure that saved much. Are there any other tricks to further reduce the file size? thanks, Steve
Hi Steve,
Good tips on how to reduce the file size and / or process time. Another thing I would definitely try is to use Data Model to load the data rather than keep it in the file. You would be,
1. connect to source data file thru Power Query
2. filter away any columns / rows that are not needed
3. load the data to model
4. make pivots from it
This would reduce the file size while providing all the answers you need.
Give it a try. See this video for some help - https://www.youtube.com/watch?v=5u7bpysO3FQ
Normally when Excel processes data it utilizes all four cores on a processor. Is it true that Excel reduces to only using two cores When calculating tables? Same issue if there were two cores present, it would reduce to one in a table?
I ask because, I have personally noticed when i use tables the data is much slower than if I would have filtered it. I like tables for obvious reasons when working with datasets. Is this true.
John:
I don't know if it is true that Excel Table processing only uses 2 threads/cores, but it is entirely possible. The program has to be enabled to handle multiple parallel threads. Excel Lists/Tables were added long ago, at a time when 2 processes was a reasonable upper limit. And, it could be that there simply is no way to program table processing to use more than 2 threads at a time...
When I've got a large data set, I will set my Excel priority to High thru Task Manager to allow it to use more available processing. Never use RealTime priority or you're completely locked up until Excel finishes.
That is a good tip Jen...