Manually create a pyspark dataframe - pyspark

Question

I am trying to manually create a pyspark dataframe given certain data:
row_in = [(1566429545575348), (40.353977), (-111.701859)]
rdd = sc.parallelize(row_in)
schema = StructType(
[
StructField("time_epocs", DecimalType(), True),
StructField("lat", DecimalType(), True),
StructField("long", DecimalType(), True),
]
)
df_in_test = spark.createDataFrame(rdd, schema)
This gives an error when I try to display the dataframe, so I am not sure how to do this.
However, the Spark documentation seems to be a bit convoluted to me, and I got similar errors when I tried to follow those instructions.
Does anyone know how to do this?

Answer 1

Simple dataframe creation:
df = spark.createDataFrame(
[
(1, "foo"), # create your data here, be consistent in the types.
(2, "bar"),
],
["id", "label"] # add your column names here
)
df.printSchema()
root
|-- id: long (nullable = true)
|-- label: string (nullable = true)
df.show()
+---+-----+
| id|label|
+---+-----+
| 1| foo|
| 2| bar|
+---+-----+
According to official doc:
when schema is a list of column names, the type of each column will be inferred from data. (example above ↑)
When schema is pyspark.sql.types.DataType or a datatype string, it must match the real data. (examples below ↓)
# Example with a datatype string
df = spark.createDataFrame(
[
(1, "foo"), # Add your data here
(2, "bar"),
],
"id int, label string", # add column names and types here
)
# Example with pyspark.sql.types
from pyspark.sql import types as T
df = spark.createDataFrame(
[
(1, "foo"), # Add your data here
(2, "bar"),
],
T.StructType( # Define the whole schema within a StructType
[
T.StructField("id", T.IntegerType(), True),
T.StructField("label", T.StringType(), True),
]
),
)
df.printSchema()
root
|-- id: integer (nullable = true) # type is forced to Int
|-- label: string (nullable = true)
Additionally, you can create your dataframe from Pandas dataframe, schema will be inferred from Pandas dataframe's types :
import pandas as pd
import numpy as np
pdf = pd.DataFrame(
{
"col1": [np.random.randint(10) for x in range(10)],
"col2": [np.random.randint(100) for x in range(10)],
}
)
df = spark.createDataFrame(pdf)
df.show()
+----+----+
|col1|col2|
+----+----+
| 6| 4|
| 1| 39|
| 7| 4|
| 7| 95|
| 6| 3|
| 7| 28|
| 2| 26|
| 0| 4|
| 4| 32|
+----+----+

Answer 2

To elaborate/build off of #Steven's answer:
field = [
StructField("MULTIPLIER", FloatType(), True),
StructField("DESCRIPTION", StringType(), True),
]
schema = StructType(field)
multiplier_df = sqlContext.createDataFrame(sc.emptyRDD(), schema)
Will create a blank dataframe.
We can now simply add a row to it:
l = [(2.3, "this is a sample description")]
rdd = sc.parallelize(l)
multiplier_df_temp = spark.createDataFrame(rdd, schema)
multiplier_df = wtp_multiplier_df.union(wtp_multiplier_df_temp)

Answer 3

This answer demonstrates how to create a PySpark DataFrame with createDataFrame, create_df and toDF.
df = spark.createDataFrame([("joe", 34), ("luisa", 22)], ["first_name", "age"])
df.show()
+----------+---+
|first_name|age|
+----------+---+
| joe| 34|
| luisa| 22|
+----------+---+
You can also pass createDataFrame a RDD and schema to construct DataFrames with more precision:
from pyspark.sql import Row
from pyspark.sql.types import *
rdd = spark.sparkContext.parallelize([
Row(name='Allie', age=2),
Row(name='Sara', age=33),
Row(name='Grace', age=31)])
schema = schema = StructType([
StructField("name", StringType(), True),
StructField("age", IntegerType(), False)])
df = spark.createDataFrame(rdd, schema)
df.show()
+-----+---+
| name|age|
+-----+---+
|Allie| 2|
| Sara| 33|
|Grace| 31|
+-----+---+
create_df from my Quinn project allows for the best of both worlds - it's concise and fully descriptive:
from pyspark.sql.types import *
from quinn.extensions import *
df = spark.create_df(
[("jose", "a"), ("li", "b"), ("sam", "c")],
[("name", StringType(), True), ("blah", StringType(), True)]
)
df.show()
+----+----+
|name|blah|
+----+----+
|jose| a|
| li| b|
| sam| c|
+----+----+
toDF doesn't offer any advantages over the other approaches:
from pyspark.sql import Row
rdd = spark.sparkContext.parallelize([
Row(name='Allie', age=2),
Row(name='Sara', age=33),
Row(name='Grace', age=31)])
df = rdd.toDF()
df.show()
+-----+---+
| name|age|
+-----+---+
|Allie| 2|
| Sara| 33|
|Grace| 31|
+-----+---+

Answer 4

With formatting
from pyspark.sql import SparkSession
from pyspark.sql.types import StructField, StructType, IntegerType, StringType
spark = SparkSession.builder.getOrCreate()
df = spark.createDataFrame(
[
(1, "foo"),
(2, "bar"),
],
StructType(
[
StructField("id", IntegerType(), False),
StructField("txt", StringType(), False),
]
),
)
print(df.dtypes)
df.show()

Answer 5

Extending #Steven's Answer:
data = [(i, 'foo') for i in range(1000)] # random data
columns = ['id', 'txt'] # add your columns label here
df = spark.createDataFrame(data, columns)
Note: When schema is a list of column-names, the type of each column will be inferred from data.
If you want to specifically define schema then do this:
from pyspark.sql.types import StructType, StructField, IntegerType, StringType
schema = StructType([StructField("id", IntegerType(), True), StructField("txt", StringType(), True)])
df1 = spark.createDataFrame(data, schema)
Outputs:
>>> df1
DataFrame[id: int, txt: string]
>>> df
DataFrame[id: bigint, txt: string]

Answer 6

for beginners, a full example importing data from file:
from pyspark.sql import SparkSession
from pyspark.sql.types import (
ShortType,
StringType,
StructType,
StructField,
TimestampType,
)
import os
here = os.path.abspath(os.path.dirname(__file__))
spark = SparkSession.builder.getOrCreate()
schema = StructType(
[
StructField("id", ShortType(), nullable=False),
StructField("string", StringType(), nullable=False),
StructField("datetime", TimestampType(), nullable=False),
]
)
# read file or construct rows manually
df = spark.read.csv(os.path.join(here, "data.csv"), schema=schema, header=True)