jcrfsuite training file format

Question

From what I understand from the example of POS Tagging given in the examples of jcrfsuite. The training file is tab separated and first token is the label. But I do not get the BigCluster| thing. Can somebody help me with how to specify tokens in training file.

Example below:

O BigCluster|00 BigCluster|0000 BigCluster|000000 BigCluster|00000000 BigCluster|0000000000 BigCluster|000000000000 BigCluster|00000000000000 BigCluster|0000000000000000 NextBigCluster|0100 NextBigCluster|01000101 NextBigCluster|010001011111 POSTagDict|D POSTagDict|N POSTagDict|^ POSTagDict|$ POSTagDict|G NextPOSTag|V 1gramSuff|i 1gramPref|i prevword| prevcurr||i nextword|predict nextword|predict currnext|i|predict Word|I Lower|i Xxdshape|X charclass|1, first-shortcap prevnext||predict t=0

Test file format:

! BigCluster|01 BigCluster|0110 BigCluster|011011 BigCluster|01101100 BigCluster|0110110011 BigCluster|011011001100 BigCluster|01101100110000 BigCluster|0110110011000000 NextBigCluster|1000 NextBigCluster|10001000 NextBigCluster|100010000000 POSTagDict|V NextPOSTag|, metaph_POSDict|N 1gramSuff|n 2gramSuff|nn 3gramSuff|mnn 4gramSuff|mmnn 5gramSuff|mmmnn 6gramSuff|ammmnn 7gramSuff|aammmnn 8gramSuff|aaammmnn 9gramSuff|daaammmnn 1gramPref|d 2gramPref|da 3gramPref|daa 4gramPref|daaa 5gramPref|daaam 6gramPref|daaamm 7gramPref|daaammm 8gramPref|daaammmn 9gramPref|daaammmnn prevword| prevcurr||daaammmnn nextword|. nextword|. currnext|daaammmnn|. Word|Daaammmnn Lower|daaammmnn Xxdshape|Xxxxxxxxx charclass|1,2,2,2,2,2,2,2,2, first-initcap prevnext||. t=0

Answer 1

What is specified after the label is a list of feature-name and feature-value. It is in a sparse representation instead of tabular representation.

BigCluster is just one of the features and it's relevant to the specific example only. You should create your own features if you are training from scratch.

Answer 2

I have noticed that CRFsuite does not care for the naming convention nor feature design of labels and attributes, because treats them as strings.

CRFsuite learns weights of associations (feature weights) between attributes and labels, without knowing the meaning of labels and attributes. In other words, one can design and use arbitrary features just by writing label and attribute names in data sets, just find the best posible attributes for your example and run some experiments with different sets of attributes and features. And you will good to go.