Creating Spark dataframe from numpy matrix

Jan Sila picture Jan Sila · Jul 12, 2017 · Viewed 12.7k times · Source

it is my first time with PySpark, (Spark 2), and I'm trying to create a toy dataframe for a Logit model. I ran successfully the tutorial and would like to pass my own data into it.

I've tried this:

%pyspark
import numpy as np
from pyspark.ml.linalg import Vectors, VectorUDT
from pyspark.mllib.regression import LabeledPoint

df = np.concatenate([np.random.randint(0,2, size=(1000)), np.random.randn(1000), 3*np.random.randn(1000)+2, 6*np.random.randn(1000)-2]).reshape(1000,-1)
df = map(lambda x: LabeledPoint(x[0], Vectors.dense(x[1:])), df)

mydf = spark.createDataFrame(df,["label", "features"])

but I cannot get rid of :

TypeError: Cannot convert type <class 'pyspark.ml.linalg.DenseVector'> into Vector

I'm using the ML library for vector and the input is a double array, so what's the catch, please? It should be fine according to the documentation.

Many thanks.

Answer

Jeff Hernandez picture Jeff Hernandez · Oct 18, 2017

From Numpy to Pandas to Spark:

data = np.random.rand(4,4)
df = pd.DataFrame(data, columns=list('abcd'))
spark.createDataFrame(df).show()

Output:

+-------------------+-------------------+------------------+-------------------+
|                  a|                  b|                 c|                  d|
+-------------------+-------------------+------------------+-------------------+
| 0.8026427193838694|0.16867056812634307|0.2284873209015007|0.17141853164400833|
| 0.2559088794287595| 0.3896957084615589|0.3806810025185623| 0.9362280141470332|
|0.41313827425060257| 0.8087580640179158|0.5547653674054028| 0.5386190454838264|
| 0.2948395900484454| 0.4085807623354264|0.6814694724946697|0.32031773805256325|
+-------------------+-------------------+------------------+-------------------+