5 tips for data manipulation in Excel

big data 14

There's plenty you can do, if you know the correct formulas.

If you work with data much, you don't need a statistical model to predict that the odds of consistently getting data in the format you need for analysis are pretty low. Those who do a great deal of data cleaning and reformatting often turn to scripting languages like Python or specialty tools such as OpenRefine or R.

But it turns out that there's a lot of data munging you can do in a plain old Excel spreadsheet -- if you know how to craft the proper formulas.

In a presentation at the recent 2014 Computer Assisted Reporting (CAR) conference, MaryJo Webster, senior data reporter with Digital First Media -- a newspaper group in New York -- shared some of her favorite Excel tricks. The goal of these tips, Webster said: Learn at least one new thing that will make you say, "Why didn't I know this before?"

Date functions

Tip 1: Split dates into separate fields

You can extract the year, month and day into separate fields from a date field in Excel by using formulas =Year(CellWithDate), =MONTH(CellWithDate) and =DAY(CellWithDate). Splitting dates this way -- by year, month and day of month -- works in Microsoft Access as well, Webster said.

In addition, you can also get the day of the week for any date in Excel with =WEEKDAY(CellWithDate). The default returns numbers, not names of the days of week, with 1 for Sunday, 2 for Monday and so on.

To display the name of the weekday instead of a number, apply a custom format to the cells with the weekday numbers, using Format cells > Custom; then type ddd in the Type text box to get three-day abbreviations or dddd for the full day name.

Tip 2: Find someone's current age

If you have someone's date of birth, you can find his or her current age on whatever day you open the spreadsheet with the =DATEDIF() and =TODAY() functions. TODAY(), as you might guess, gives the current date. DATEDIF() gives the difference between two dates in units of years ("y"), months ("m") or days ("d"), using the syntax:

=DATEDIF(Date1, Date2, Unit of measure)

So, to get current age in years, use the formula:

=DATEDIF(CellWithBirthday,TODAY(), "y")

Note that the years unit returns ages in whole numbers and does not round up.

See an example below.

If you have someone's date of birth, you can find his or her current age.

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