How to do boolean slicing in Pandas

Question

I have a dataframe. I would like to slice based on a comparison between the 2 columns. For instance in the following example I would like to extract rows where column x is larger than column y:

d = pd.DataFrame({'x':[1, 2, 3, 4, 5], 'y':[4, 5, 6, 7, 8]})

d[d[:"x"]>d[:"y"]]

By doing so I get an error:

"unhashable type: 'slice'"

Answer 1

You need omit : and use boolean indexing:

d[d["x"]>d["y"]]

Sample (changed last value):

d = pd.DataFrame({'x':[1, 2, 3, 4, 5], 'y':[4, 5, 6, 7, 3]})
print (d)
   x  y
0  1  4
1  2  5
2  3  6
3  4  7
4  5  3

print (d["x"]>d["y"])
0    False
1    False
2    False
3    False
4     True
dtype: bool

print (d[d["x"]>d["y"]])
   x  y
4  5  3