how to send an array over a socket in python

I solved this problem using json (since I heard pickle is unsafe)

client:

import json
...
arr1 = [1,2,3]
arr2 = [4,5,6]
someVar = 7
data = json.dumps({"a": arr1, "b": arr2, "c": someVar})
socket.send(data.encode())

server:

import json
...
data = socket.recv(1024)
data = json.loads(data.decode())
arr = data.get("a")
var = data.get("c")

Here we deserialize the json string, using data.get("a") which you can interpret as data.a

You can Serialize the object before sending to socket and at receiving end Deserialize it. Check this

Sockets are byte streams, so ideal is to write your protocol (read this)

This is a basic example without protocol and you should care about buffer -> recv(). If it is too small, your data will be chopped off. That's why you should implement a protocol, if you send unknown size of data.

Client:

import socket, pickle

HOST = 'localhost'
PORT = 50007
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST, PORT))
arr = ([1,2,3,4,5,6],[1,2,3,4,5,6])
data_string = pickle.dumps(arr)
s.send(data_string)

data = s.recv(4096)
data_arr = pickle.loads(data)
s.close()
print 'Received', repr(data_arr)

Server:

import socket

HOST = 'localhost'
PORT = 50007
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((HOST, PORT))
s.listen(1)
conn, addr = s.accept()
print 'Connected by', addr
while 1:
    data = conn.recv(4096)
    if not data: break
    conn.send(data)
conn.close()