Time Formatting in columns

Question

I have a column with times in it. I have selected the format that is X:XX AM/PM. However, when I sort the column by time, it also sorts by the date stamp on it, even though the date is not included in the format I have selected. For instance, when I created the document on March 8, it included that date automatically. When I changed some of the times when working on it the next day, it also changed the date. Now when I sort, those times appear at the end of the document. Is there anyway to get rid of the date stamp that numbers seems to automatically place on the cell contents?

Answer 1

Formatting the value in a cell changes how that value is displayed, but does not affect the value itself (with the exception noted in discussion f column E in the first set of examples).
Any cell where a date or a time has been entered (or calculated) contains a Date and Time value.
If only the Date has been entered, the time part is set to 00:00:00 (midnight, at the start of that date).
If only the Time has been entered, the date part is set to the date of the entry.
As Wayne suggests, you can reformat these cells as Text. Once that's done, you can edit the text to show only the part you want to show:
Here the values shown in column B were entered directly. These three values were then copied, and pasted into columns C, D and E.
All three columns were then formatted as Text, with the results seen in column C. Note that the 2:03PM time entry includes today's date.
Columns D and E were then edited to remove the representation of the date, with the results seen in column D.
Finally column E's format was reset to Automatic, with the resulting display.
Mathematically, column D gives trhe expected results of subtracting one time from another. But leaving the values as text introduces another issue.
Formatted as Text, the values in this column follow Text sorting rules, resulting in the unexpected result seen in the second table below.
Roows 3 and 4 sorted ascending on the entry column (column B). March 16 is before March 18 (the hidden date in row 4), so it comes first in the list.
Sorting these two rows in ascending order on the text values in column C gives the same order: 16... is 'alphabetically' before 18.... Note though, that March 3, 2013 (3/3/2013...) would sort alphabetically after March 18 (18/3/2013) as 1... is 'alphabetically' before 3.....
Sorted the same rows on the text values in column D reverses the two times. 'alphabetically', 2:0... comes before 2:1...
When the text values are changed to Automatic format, Numbers interprets the entries as dates (E2) or times (E3 and E4) and completes the Date and Time values following the usual rules.
Row 6 shows the results of subtracting B3 from B4 (in column B). Two things to note:
Numbers correctly recognizes the text in columns C and D as showing Date and Time values (column C) or the Time parts of Date and Time values (column D), appends the missing part, where necessary, and correctly completes the subtraction.
Numbers follows the referenced cells through their positional changes in a sort, and keeps the cell references pointing to the original cell in its new position. The results of the subtraction do not change.
An alternate method of stripping dates from Date and Time values:
One means of removing the effects of the date part of the value is to use TIMEVALUE(B2) to extract a decimal value representing the time as the fraction of the current day that has passed to that time.
Placed into an auxiliary column used for sorting, this will correctly sort rows in order of ascending (earlier to later) time od day, disregarding the date.
Used in a subtraction formula, the difference will be a number which can be multiplied by 24 to give the number of hours (and decimal parts of an hour) between the two times, or multiplied by 1440 to give the number of minutes (and decimal parts of minutes, if any) between the two times.
Regards,
Barry