Help using the Pick lists on subset list page

## Picking from the drop-down menus: examples

Using 'AND' to combine multiple selections
Using 'OR' to combine multiple selections and projections
The string operators
Using the string operators
Combining string and numeric operators
Combining string and numeric selections together with projections

Using 'AND' to combine multiple selections

You want to:

Select all values at stations numbered greater than 1 AND (indicated by the comma)
at depths equal to or less than 100 meters deep.
The subset list to use is:

  sta > 1, depth <= 100

Pick list technique

- First, pull down the list of variables under 'Selections:' and click on 'sta'.
- Then, at the next pull-down list, choose the operator '>'
- Next, type the value '1' in the area following the '>'
- Finally, push the 'Add selection' button.
- Continue, by adding the 'depth <= 100' selection, making certain
  on this second selection that the 'AND' combination value is selected,
- Then click 'Add selection'.
- Double check that the subset list as displayed near the top of the screen is exactly what you want.

Having completed your entry of a new subset list, click on the link 'Continue using new subset list' at the bottom of the page. This will allow you to Plot or Map or Join, etc. with only those values of interest to you.

Using 'OR' to combine multiple selections and projections

You want to:

Select all data from stations numbered 1 OR 2 OR 3, and only view values for station, depth and temperature,
(the vertical bar "|" indicates OR)
The subset list to use is:

  sta = 1 | sta = 2 | sta = 3, sta, depth, temp
  spaces above are presented to improve readability and do NOT exist in the command

Pick list technique

- First, pull down the list of variables under 'Selections:' and click on 'sta'.
- Then, at the next pull-down list, choose the operator '='
- Next, type the value '1' in the area following the '='
- Finally, push the 'Add selection' button.
- Pull down list and click on 'sta' (again)
- Choose operator '=' (again)
- Type in '2'
- Now, you must choose the value 'OR' for combining with existing, active selections
- then click 'Add selection'.
- Repeat for 'sta = 3'
- Moving to the right-hand column to perform the projections:
- Click on 'sta', then click on 'depth' and 'temp' in the list of variables presented
- Note: depending on your browser, you may need to hold the Shift key
  or the Control key to choose multiple entries from a list.
- Finally, click on 'Add projection(s)'.
- Double check that the subset list as displayed near the top of the screen is exactly what you want.

Having completed your entry of a new subset list, click on the link 'Continue using new subset list' at the bottom of the page. This will allow you to Plot or Map or Join, etc. with only those values of interest to you.

The string operators

Please note:

Not all string operators are available for all data sets. Unfortunately, you won't know if the operator
you want is available until a few menus after this one, and the failure may not be clearly associated
with the string operator

The string operators allow you more control over comparisons, especially when you want to select data
stored in alphanumeric strings.

The string operators force comparisons as text strings, whereas numeric operators will compare things
numerically if possible. For example, if a datum were the string "051099", the selection
- datum=51099
would select the datum, while the selection
- datum eq 51099
would not. (you'd need to say 'datum eq 051099')

The lower case string operators perform comparisons in a case-sensitive manner. The upper case
string operators perform comparisons in a case-blind manner.

The like operator offers sql-like wild card capability

Using the string operators

You want to:

Select all stations that have a "N" in the station identifier
(given that the data contains a station identifier comprised of letters as well as numbers).
The subset list to use is:

  station contains N

Pick list technique

- First, pull down the list of variables under 'Selections:' and click on 'station'.
- Then, at the next pull-down list, choose the operator, 'contains'
- Next, moving across the screen to the right, type the value 'N' in the available space
- Finally, push the 'Add selection' button.
- Double check that the subset list as displayed near the top of the screen is exactly what you want.

Having completed your entry of a new subset list, click on the link 'Continue using new subset list' at the bottom of the page. This will allow you to Plot or Map or Join, etc. with only those values of interest to you.

Combining string and numeric operators

You want to:

Select all values on cruises beginning with "AL" and only from deep water.
The subset list to use is:

  cruise_id begins_with AL,depth>1000

Pick list technique

- First, pull down the list of variables under 'Selections:' and click on 'cruise_id'.
- Then, at the next pull-down list, choose the operator, 'begins_with'
- Next, moving across the screen to the right, type the value 'AL' in the available space
- Then, push the 'Add selection' button.
- Returning to the same are of the screen, Pull down the list of variables, and click on 'depth'
- Then, at the next pull-down list, choose the operator, '>'
- Next, type the value '1000' in the available space
- Make certain on this second selection that the 'AND' combination value is selected
- Then click 'Add selection'.
- Double check that the subset list as displayed near the top of the screen is exactly what you want.

Having completed your entry of a new subset list, click on the link 'Continue using new subset list' at the bottom of the page. This will allow you to Plot or Map or Join, etc. with only those values of interest to you.

Combining string and numeric selections, together with projections.

You want to:

Select only latitude, longitude, date, pressure, temperature and salinity values on cruises beginning with 'TN' and only from the upper water column.
The subset list to use is:

  cruise_id begins_with TN,press<300,lat,lon,date,press,temp,sal

Pick list technique

- First, pull down the list of variables under 'Selections:' and click on 'cruise_id'.
- Then, at the next pull-down list, choose the operator, 'begins_with'
- Next, moving across the screen to the right, type the value 'TN' in the available space
- Then, push the 'Add selection' button.
- Returning to the same area of the screen, Pull down the list of variables, and click on 'press'
- Then, at the next pull-down list, choose the operator, '<'
- Next, type the value '300' in the available space
- Make certain on this second selection that the 'AND' combination value is selected
- Then click 'Add selection'.
- Moving to the right-hand column to perform the projections:
- Click on 'lat', then click on 'lon','date','press','temp','sal' in the list of variables presented
- Note: depending on your browser, you may need to hold the Shift key
  or the Control key to choose multiple entries from a list.
- Finally, click on 'Add projection(s)'.
- Double check that the subset list as displayed near the top of the screen is exactly what you want.

Having completed your entry of a new subset list, click on the link 'Continue using new subset list' at the bottom of the page. This will allow you to Plot or Map or Join, etc. with only those values of interest to you.

Last modified 6 Nov 09