Column with dates

[#1]

Hello,

I've these columns:

I would like to build a graph with de "Difference" on the axis Y (continuous values).

it doen't work because the format is "caracter".

How can I do it?

thanks for your help.

Françoise

[#2]

You can easily convert all 3 of your columns into proper Date/Time columns for "Date hour preparation" and "date hour use" and into a duration column for the column called "Difference".  

I will start with the column "Difference"

1. Right click on the column header for column "Difference" and choose "Column Info".  You will see the following screen

2. Change the Data Type to Numeric. (A New format field will be displayed)

3. Change the Modeling Type to Coninuous

4. Change the Format to

     Duration==>hr:m

The window will now look like

5. Click on the "Apply" button and the Difference Column will be changed to Numeric/Continuous

You can repeat the above steps for the 2 date/time columns, but instead of selecting a Duration format, select 

     Time==>d/m/y h:m

Which results in a data table looking like

[#3]

ok, but when I change the data type in continuous numeric for the column "Difference", the values disappear!

[#4]

That is one of things that happen when you change a column from categorical to numeric.  You can quickly recalculate the difference in a new column by highlighting the two columns of interest and then doing a right click in the column header area and selecting New Formula Column > Combine > Difference.  A new column will be added to your data table with the difference.  If that doesn't look exactly right try Difference (reverse order).

HTH

[#5]

I can't do it.

can you dio it in the file" exemple.jmp"?

[#6 · Accepted solution]

my assumption is that you selected a column format that didn't match properly

[#7 · Accepted solution]

To add to @txnelson's response and his previous images.  All of your data types need to be converted to continuous for the difference calculation to work.