Groups

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It is often useful to place and display samples in groups.

 

For example, in the graph below, the species of fish caught in different years are split into several groups and displayed as different colours.

 

pcahink

 

Choose Edit|Groups from the drop-down menu to create groups and assign individual samples to groups.

 

Assignment to groups.

 

1. First type a name for a group in the box to the right of the label 'Enter name here'. We have added the word Estuarine.

 

EditGroups

 

 

2. Select a sample to allocate to this group from the left-hand list of samples in the data set: here we have selected Hinkley..

 

edit2

 

3. Click the Assign To Group button and the selected site is added to the group.

 

4. Blocks of samples can be assigned by clicking on the first sample required in the left hand column of numbers, holding down the left hand mouse button and dragging the cursor down to select a group, and then Clicking on Assign to Group.

 

edit3

 

To save the group allocations remember to save your dataset from the File menu. As well as creating the main data set, this will create a file of the same name as your main data file, with the .pcg file extension; your group assignments will be saved with your data.

 

You can remove individual samples from a group, or all group assignments, using the Unassign Selected and  Unassign All buttons. If you wish to alter group names, you can remove any group name by selecting it in the 'List of group names' box and clicking the Delete Selected Group button. The group members for that group will revert to 'Unassigned'.

You can sort your samples by Group or Name using the two buttons above the sample list.

 

NOTE: If you have allocated your samples to groups, you will find that your groups will be lost if you transpose your data. The solution is to save your working data using File | Export, then reload the data into ECOM; you can then re-assign samples to groups. 

 

The data that controls the membership of groups is held in a file with the extension .pcg. There is one group file created for each data set saved from ECOM. The .pcg file is not meant to be edited manually, but via the Edit Group dialog within the program.

 

It is a text file with the following format:

 

Sample Name, Group Name, ""

 

Note that there are no headers on the columns. As an example:

3784,Rich Acres,""

4128,Rich Acres,""

4132,Rich Acres,""

4428,Quartz Gabbro,""

4436,Quartz Gabbro,""

44.44,Quartz Gabbro,""

4441,Hybrid,""

4445,Hybrid,""

 

 

If no groups have been set then each sample belongs to a group called Unassigned; e.g.:

 

G1,Unassigned,""

G2,Unassigned,""

X1,Unassigned,""

X2,Unassigned,""

 

 

When you have performed an analysis, if you enable the plot legend, the groups will be displayed on the legend.

 

If you wish, you can change the order in which the Groups are displayed; click the Edit Chart button, and on the Series tab, select a Group, and use the Up or Down arrow to move it into the order you want:

 

editgrouporder2