struct

struct.pack gives different results when calling it again after reassigning one of its inputs Question: I am writing a Python script to send ICMP packets by following an example from a Japanese website. There is part of the code where struct.pack is used to pack series of variables into a bytes array. It looks somehow …

Python equivalent of C struct for writing bytes to a file Question: What could be the simplest Python equivalent to the following C code? #include <stdio.h> int main(void) { struct dog { char breed[16]; char name[16]; }; struct person { char name[16]; int age; struct dog pets[2]; }; struct person p = { "John Doe", …

Reading "a flat, binary array of 16-bit signed, little-endian (LSB) integers" from file in python Question: I’m trying to read a old file of snow data from here, but I’m having a ton of trouble just opening a single file and getting data out. In the user guide, it says "Each monthly binary data file …

How can I create this struct? Question: I want to create a struct like this: import ctypes class MyStruct(ctypes.Structure): _fields_ = [(‘field1’, /* size of 16 bytes */), (‘field2’, /* size of 4 bytes */) (‘field3’, /* size of 8 bytes */)] What is the types that i need to write here for these sizes …

How to rename the first level keys of struct with PySpark in Azure Databricks? Question: I would like to rename the keys of the first level objects inside my payload. from pyspark.sql.functions import * ds = {‘Fruits’: {‘apple’: {‘color’: ‘red’},’mango’: {‘color’: ‘green’}}, ‘Vegetables’: None} df = spark.read.json(sc.parallelize([ds])) df.printSchema() """ root |– Fruits: struct (nullable = …

Get the first two words from a struct in PySpark data frame Question: data=[(("James","Bond"),["Java","C#"],{‘hair’:’black’,’eye’:’brown’}), (("Ann","Varsa"),[".NET","Python"],{‘hair’:’brown’,’eye’:’black’}), (("Tom Cruise",""),["Python","Scala"],{‘hair’:’red’,’eye’:’grey’}), (("Tom Brand",None),["Perl","Ruby"],{‘hair’:’black’,’eye’:’blue’})] schema = [‘n’,’ln’,’p’] df = spark.createDataFrame(data,schema=schema) +—————–+—————+——————–+ | n| ln| p| +—————–+—————+——————–+ | {James, Bond}| [Java, C#]|{eye -> brown, ha…| | {Ann, Varsa}| [.NET, Python]|{eye -> black, ha…| | {Tom Cruise, }|[Python, Scala]|{eye -> grey, hai…| …

Does struct.pack(f'{len(x)}s', x) do anything at all? Question: Consider the following code: import struct x = b’example’ # can be any bytes object y = struct.pack(f'{len(x)}s’, x) print(x == y) If I understand the documentation correctly, the function call will return the binary representation of a struct that has an array of len(x) chars (that …

Give prefix to all columns when selecting with 'struct_name.*' Question: The dataframe below is a temp_table named: ‘table_name’. How would you use spark.sql() to give a prefix to all columns? root |– MAIN_COL: struct (nullable = true) | |– a: string (nullable = true) | |– b: string (nullable = true) | |– c: string …

Unpacking ripemd160 result in python Question: I am working on a program which does a lot of hashing, and in one of the steps I take a result of hashlib’s ripemd160 hash and convert it into an integer. The lines are: ripe_fruit = new(‘ripemd160’, sha256(key.to_der()).digest()) key_hash160 = struct.unpack(“<Q”, ripe_fruit.digest())[0] It gives me the error: struct.error: …

C to Python via Ctypes – Wrapping Struct of Function Pointers to Static Functions Question: I have structs in a C library that are like this. The function pointers in DataFn point to static functions. .h struct Data { int i; int *array; }; typedef struct { bool (* const fn1) (struct Data*, const char …