ValueError：サイズ2のシーケンスを次元4の配列軸にコピーできません
このエラーの原因を誰かに説明してもらえますか？そしてそれはどういう意味ですか？どうすればそれを修正できますか？多分私の質問はとても一般的です！申し訳ありませんが、ここに何を追加すればよいかわかりません。 ：P
エラー：
Traceback (most recent call last):
File "C:\test\7.4.3.bench.py", line 9, in <module>
print imagesearch.compute_ukbench_score(src,imlist[:100])
File "C:\test\imagesearch.py", line 168, in compute_ukbench_score
pos[i] = [w[1]-1 for w in src.query(imlist[i])[:4]]
File "C:\test\imagesearch.py", line 128, in query
h = self.get_imhistogram(imname)
File "C:\test\imagesearch.py", line 91, in get_imhistogram
"select rowid from imlist where filename='%s'" % imname).fetchone()
ValueError: cannot copy sequence with size 2 to array axis with dimension 4
これがimagesearch.pyです：
from numpy import *
import pickle
from pysqlite2 import dbapi2 as sqlite
class Indexer(object):
def __init__(self,db,voc):
""" Initialize with the name of the database
and a vocabulary object. """
self.con = sqlite.connect(db)
self.voc = voc
def __del__(self):
self.con.close()
def db_commit(self):
self.con.commit()
def get_id(self,imname):
""" Get an entry id and add if not present. """
cur = self.con.execute(
"select rowid from imlist where filename='%s'" % imname)
res=cur.fetchone()
if res==None:
cur = self.con.execute(
"insert into imlist(filename) values ('%s')" % imname)
return cur.lastrowid
else:
return res[0]
def is_indexed(self,imname):
""" Returns True if imname has been indexed. """
im = self.con.execute("select rowid from imlist where filename='%s'" % imname).fetchone()
return im != None
def add_to_index(self,imname,descr):
""" Take an image with feature descriptors,
project on vocabulary and add to database. """
if self.is_indexed(imname): return
print 'indexing', imname
# get the imid
imid = self.get_id(imname)
# get the words
imwords = self.voc.project(descr)
nbr_words = imwords.shape[0]
# link each Word to image
for i in range(nbr_words):
Word = imwords[i]
# wordid is the Word number itself
self.con.execute("insert into imwords(imid,wordid,vocname) values (?,?,?)", (imid,Word,self.voc.name))
# store Word histogram for image
# use pickle to encode NumPy arrays as strings
self.con.execute("insert into imhistograms(imid,histogram,vocname) values (?,?,?)", (imid,pickle.dumps(imwords),self.voc.name))
def create_tables(self):
""" Create the database tables. """
self.con.execute('create table imlist(filename)')
self.con.execute('create table imwords(imid,wordid,vocname)')
self.con.execute('create table imhistograms(imid,histogram,vocname)')
self.con.execute('create index im_idx on imlist(filename)')
self.con.execute('create index wordid_idx on imwords(wordid)')
self.con.execute('create index imid_idx on imwords(imid)')
self.con.execute('create index imidhist_idx on imhistograms(imid)')
self.db_commit()
class Searcher(object):
def __init__(self,db,voc):
""" Initialize with the name of the database. """
self.con = sqlite.connect(db)
self.voc = voc
def __del__(self):
self.con.close()
def get_imhistogram(self,imname):
""" Return the Word histogram for an image. """
im_id = self.con.execute(
"select rowid from imlist where filename='%s'" % imname).fetchone()
s = self.con.execute(
"select histogram from imhistograms where rowid='%d'" % im_id).fetchone()
# use pickle to decode NumPy arrays from string
return pickle.loads(str(s[0]))
def candidates_from_Word(self,imword):
""" Get list of images containing imword. """
im_ids = self.con.execute(
"select distinct imid from imwords where wordid=%d" % imword).fetchall()
return [i[0] for i in im_ids]
def candidates_from_histogram(self,imwords):
""" Get list of images with similar words. """
# get the Word ids
words = imwords.nonzero()[0]
# find candidates
candidates = []
for Word in words:
c = self.candidates_from_Word(word)
candidates+=c
# take all unique words and reverse sort on occurrence
tmp = [(w,candidates.count(w)) for w in set(candidates)]
tmp.sort(cmp=lambda x,y:cmp(x[1],y[1]))
tmp.reverse()
# return sorted list, best matches first
return [w[0] for w in tmp]
def query(self,imname):
""" Find a list of matching images for imname. """
h = self.get_imhistogram(imname)
candidates = self.candidates_from_histogram(h)
matchscores = []
for imid in candidates:
# get the name
cand_name = self.con.execute(
"select filename from imlist where rowid=%d" % imid).fetchone()
cand_h = self.get_imhistogram(cand_name)
cand_dist = sqrt( sum( self.voc.idf*(h-cand_h)**2 ) )
matchscores.append( (cand_dist,imid) )
# return a sorted list of distances and database ids
matchscores.sort()
return matchscores
def get_filename(self,imid):
""" Return the filename for an image id. """
s = self.con.execute(
"select filename from imlist where rowid='%d'" % imid).fetchone()
return s[0]
def tf_idf_dist(voc,v1,v2):
v1 /= sum(v1)
v2 /= sum(v2)
return sqrt( sum( voc.idf*(v1-v2)**2 ) )
def compute_ukbench_score(src,imlist):
""" Returns the average number of correct
images on the top four results of queries. """
nbr_images = len(imlist)
pos = zeros((nbr_images,4))
# get first four results for each image
for i in range(nbr_images):
pos[i] = [w[1]-1 for w in src.query(imlist[i])[:4]]
# compute score and return average
score = array([ (pos[i]//4)==(i//4) for i in range(nbr_images)])*1.0
return sum(score) / (nbr_images)
# import PIL and pylab for plotting
from PIL import Image
from pylab import *
def plot_results(src,res):
""" Show images in result list 'res'. """
figure()
nbr_results = len(res)
for i in range(nbr_results):
imname = src.get_filename(res[i])
subplot(1,nbr_results,i+1)
imshow(array(Image.open(imname)))
axis('off')
show()
imagesearch.pyの168行目は問題があるように見えます：
pos[i] = [ w[1]-1 for w in src.query(imlist[i]) [:4] ]
ここで発生している可能性があるのは、dbクエリが4項目未満の行を返していることです。そして、リスト内包表記で、それを4列のposの行に挿入しようとしています（したがって、そこにない4つの項目が必要です）。したがって、エラー：「ValueError：サイズ2のシーケンスを次元4の配列軸にコピーできません」
クエリステートメントのo/pを出力して、この仮説をテストします。本当に4つのアイテムがあるかどうかを確認してください。
そして、2つの項目が見つかった場合は、posへの割り当てを回避します。
l = [ w[1]-1 for w in src.query(imlist[i]) [:4] ]
if len(l) == 4:
pos[i] = l