[PYTHON] Note that the Pandas loc specifications have changed

data = [[1,2,3],[4,5,6],[7,8,9]]
col = ['A','C','E']
df = pd.DataFrame(data, columns=col)
#   A  C  E
#0  1  2  3
#1  4  5  6
#2  7  8  9

In Pandas 0.23 and earlier, on the other hand, if you specify A, B, C in the item with loc, All item names not in the data were created as missing values.

sel_col = ['A','B','C']
print(df.loc[:,sel_col])
#version 0.Before 23
#   A   B  C
#0  1 NaN  2
#1  4 NaN  5
#2  7 NaN  8

However, since Pandas 1.0, the following error has come out.

Apparently, you shouldn't specify items that aren't in the data frame. If you want to create a missing item in the data frame as before, you can use reindex instead.

sel_col = ['A','B','C']
print(df.reindex(columns=sel_col))
#   A   B  C
#0  1 NaN  2
#1  4 NaN  5
#2  7 NaN  8

Or if you want to display only the items included in the data frame, do as follows It seems that it is possible to intersect the item of the data frame and the specified item.

print(df.loc[:,df.columns.intersection(sel_col)])
#   A  C
#0  1  2
#1  4  5
#2  7  8