9/16/2023 0 Comments Create dataframe from dictionaryThe above DataFrame object has a single row and four columns. And the keys in the dictionary will become the column labels by default. If we haven’t mentioned the index values then it will rise “ValueError”. In this following example, the dictionary ‘data’ is having only scalar values so that we need to mention the index labels explicitly. Example # importing the pandas packageĭf = pd.DataFrame(data, index=) The ‘df’ DataFrame object output is displayed in the above block, as we see that the column labels “int's, float's” are from dictionary keys and the values present in DataFrame are taken from dictionary values of the data variable. In the given dictionary the keys have string data “int's, float's” and the values of the dictionary are loaded with list integer and float values. The variable data has a python dictionary object with keys and value pair, here the keys of the dictionary are represented as column labels, and values of the dictionary are represented as row data in the resultant DataFrame. Here we will create a DataFrame using a python dictionary, Let’s see the below example. Same as data tables, pandas DataFrames also have rows and columns and each column and rows are represented with labels.īy using the python dictionary we can create our own pandas DateFrame, here keys of the dictionary will become the column labels, and values will be the row data. Key won’t accept null/None values whereas map of the key can have None/Null value.DataFrame is used to represent the data in two-dimensional data table format. MapType is a map data structure that is used to store key key-value pairs similar to Python Dictionary (Dic), keys and values type of map should be of a type that extends DataType. KeysList = (lambda x:x).collect()įrom import map_valuesĭf.select(df.name,map_values(df.properties)).show() KeysDF = df.select(explode(map_keys(df.properties))).distinct() when we need the keys in the dictionary object as rows in the resultant DataFrame. Note: This method is useful for the cases when you need to transpose the DataFrame i.e. WARNING: This runs very slow.įrom import explode,map_keys This is another way of creating DataFrame from a Python dictionary using omdict () method. In case if you wanted to get all map keys as Python List. 4.1 – explodeįrom import explodeĭf.select(df.name,explode(df.properties)).show()įrom import map_keysĭf.select(df.name,map_keys(df.properties)).show() withColumn("eye",df.properties) \īelow are some of the MapType Functions with examples. withColumn("eye",df.properties.getItem("eye")) \ĭf.withColumn("hair",df.properties) \ Let’s use another way to get the value of a key from Map using getItem() of Column type, this method takes a key as an argument and returns a value.ĭf.withColumn("hair",df.properties.getItem("hair")) \ Here I have used PySpark map transformation to read the values of properties (MapType column) Let’s see how to extract the key and values from the PySpark DataFrame Dictionary column. | |- value: string (valueContainsNull = true) ('James',),ĭf = spark.createDataFrame(data=dataDictionary, schema = schema)ĭf.printSchema() yields the Schema and df.show() yields the DataFrame output. Now let’s create a DataFrame by using above StructType schema. StructField('properties', MapType(StringType(),StringType()),True) Let’s see how to create a MapType by using PySpark StructType & StructField, StructType() constructor takes list of StructField, StructField takes a fieldname and type of the value.įrom import StructField, StructType, StringType, MapType PySpark provides several SQL functions to work with MapType.The key of the map won’t accept None/Null values.Third parm valueContainsNull is an optional boolean type that is used to specify if the value of the second param can accept Null/None values.The Second param valueType is used to specify the type of the value in the map.The First param keyType is used to specify the type of the key in the map.MapCol = MapType(StringType(),StringType(),False) In order to use MapType data type first, you need to import it from and use MapType() constructor to create a map object.įrom import StringType, MapType for e.g StringType, IntegerType, ArrayType, MapType, StructType (struct) e.t.c. keyType and valueType can be any type that extends the DataType class. PySpark MapType is used to represent map key-value pair similar to python Dictionary (Dict), it extends DataType class which is a superclass of all types in PySpark and takes two mandatory arguments keyType and valueType of type DataType and one optional boolean argument valueContainsNull.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |