how to convert pandas dataframe to libsvm format? - pandas

Question

I have pandas data frame like below.
df
Out[50]:
0 1 2 3 4 5 6 7 8 9 ... 90 91 92 93 94 95 96 97 \
0 0 0 0 0 0 0 0 0 0 0 ... 1 1 1 1 1 1 1 1
1 0 1 1 1 0 0 1 1 1 1 ... 0 0 0 0 0 0 0 0
2 1 1 1 1 1 1 1 1 1 1 ... 0 0 0 0 0 0 0 0
3 0 0 0 0 0 0 0 0 0 0 ... 1 1 1 1 1 1 1 1
4 0 0 0 0 0 0 0 0 0 0 ... 1 1 1 1 1 1 1 1
5 1 0 0 1 1 1 1 0 0 0 ... 0 0 0 0 0 0 0 0
6 0 0 0 0 0 0 0 0 0 0 ... 1 1 1 1 1 1 1 1
7 0 0 0 0 0 0 0 0 0 0 ... 1 1 1 1 1 1 1 1
[8 rows x 100 columns]
I have target variable as an array as below.
[1, -1, -1, 1, 1, -1, 1, 1]
How can I map this target variable to a data frame and convert it into lib SVM format?.
equi = {0:1, 1:-1, 2:-1,3:1,4:1,5:-1,6:1,7:1}
df["labels"] = df.index.map[(equi)]
d = df[np.setdiff1d(df.columns,['indx','labels'])]
e = df.label
dump_svmlight_file(d,e,'D:/result/smvlight2.dat')er code here
ERROR:
File "D:/spyder/april.py", line 54, in <module>
df["labels"] = df.index.map[(equi)]
TypeError: 'method' object is not subscriptable
When I use
df["labels"] = df.index.list(map[(equi)])
ERROR:
AttributeError: 'RangeIndex' object has no attribute 'list'
Please help me to solve those errors.

Answer 1

I think you need convert index to_series and then call map:
df["labels"] = df.index.to_series().map(equi)
Or use rename of index:
df["labels"] = df.rename(index=equi).index
All together:
For difference of columns pandas has difference:
from sklearn.datasets import dump_svmlight_file
equi = {0:1, 1:-1, 2:-1,3:1,4:1,5:-1,6:1,7:1}
df["labels"] = df.rename(index=equi).index
e = df["labels"]
d = df[df.columns.difference(['indx','labels'])]
dump_svmlight_file(d,e,'C:/result/smvlight2.dat')
Also it seems label column is not necessary:
from sklearn.datasets import dump_svmlight_file
equi = {0:1, 1:-1, 2:-1,3:1,4:1,5:-1,6:1,7:1}
e = df.rename(index=equi).index
d = df[df.columns.difference(['indx'])]
dump_svmlight_file(d,e,'C:/result/smvlight2.dat')