Appendix A. Penn Treebank Part-of-speech Tags

The following is a table of all the part-of-speech tags that occur in the treebank corpus distributed with NLTK. The tags and counts shown here were acquired using the following code:

>>> from nltk.probability import FreqDist
>>> from nltk.corpus import treebank
>>> fd = FreqDist()
>>> for word, tag in treebank.tagged_words():
...	   fd[tag] += 1
>>> fd.items()

The FreqDist fd contains all the counts shown here for every tag in the treebank corpus. You can inspect each tag count individually, by doing fd[tag], for example, fd['DT']. Punctuation tags are also shown, along with special tags such as -NONE-, which signifies that the part-of-speech tag is unknown. Descriptions of most of the tags can be found at the following link:

http://www.ling.upenn.edu/courses/Fall_2003/ling001/penn_treebank_pos.html

Part-of-speech tag	Frequency of occurrence
#	16
$	724
''	694
,	4886
-LRB-	120
-NONE-	6592
-RRB-	126
.	384
:	563
''	712
CC	2265
CD	3546
DT	8165
EX	88
FW	4
IN	9857
JJ	5834
JJR	381
JJS	182
LS	13
MD	927
NN	13166
NNP	9410
NNPS	244
NNS	6047
PDT	27
POS	824
PRP	1716
PRP$	766
RB	2822
RBR	136
RBS	35
RP	216
SYM	1
TO	2179
UH	3
VB	2554
VBD	3043
VBG	1460
VBN	2134
VBP	1321
VBZ	2125
WDT	445
WP	241
WP$	14
WRB	178