"ValueError: arrays must all be same length" - pandas

Question

In a machine learning project, suppose I have 3 cat images and 2 dog images. when I make a dataframe for the training data.
#pre processing train data
filenames = os.listdir('/content/train')
categories = []
for filename in os.listdir('/content/train'):
category = filename.split('.')[0]
if category == 'dog' :
categories.append(1) #1 for dog and 0 for cat
else :
categories.append(0)
#make a dictonary
df = pd.DataFrame(
{
'filename' : filenames,
'category':categories
}
)
It gives an error because I haven't the same amount of dog, cat images.
ValueError Traceback (most recent call last)
<ipython-input-28-2d4e2440ba41> in <module>()
12 {
13 'filename' : filenames,
---> 14 'category' : categories
15 }
16 )
3 frames
/usr/local/lib/python3.6/dist-packages/pandas/core/internals/construction.py in extract_index(data)
395 lengths = list(set(raw_lengths))
396 if len(lengths) > 1:
--> 397 raise ValueError("arrays must all be same length")
398
399 if have_dicts:
ValueError: arrays must all be same length
Is there any way to fix it without adding any image to the training dataset?