DataFrame.replace: TypeError: Cannot compare types 'ndarray(dtype=int64)' and 'unicode'
#### Code Sample, a copy-pastable example if possible

```
path1 = '/some.xls'
df1 = pd.read_excel(path1)
columns_values_map={
    'positive': {
        '正面':1,
        '中立': 1,
        '负面':0
    }
}

df1.replace(columns_values_map)
```

#### Problem description

got error: `TypeError: Cannot compare types 'ndarray(dtype=int64)' and 'unicode'`

Actually `df1['positive']` only has value in (0, 1) , but I think it should not throw exception here.
