Fit a dataframe into randomForest pyspark

I have a DataFrame that looks like this:

+--------------------+------------------+
|            features|           labels |
+--------------------+------------------+
|[-0.38475, 0.568...]|          label1  |
|[0.645734, 0.699...]|          label2  |
|     .....          |          ...     |
+--------------------+------------------+

Both columns are of String type (StringType()), I would like to fit this into spark ml randomForest. To do so, I need to convert the features columns into a vector containing floats. Does any one have any idea How to do so ?