How to get network hash rate of ethereum blockchain via geth console or web3

Question

I want to know about how can i get ethereum blockchain network hash rate via geth console or web3.
Like the result of this api - https://www.etherchain.org/api/miningEstimator

{
 "blocktime":"14.4444282592862345",
 "difficulty":"1846255676466184.9397",
 "hashrate":"137494795284766.6526554599708515"
}

Answer 1

The way of deriving the information can be found here. So via the console,

function getNetworkStats(
        sampleSize //!< [in] Larger n give more accurate numbers but with longer latency.
    ) {
    blockNum = eth.blockNumber; // Save this value to atomically get a block number.
    blockTime = (eth.getBlock(blockNum).timestamp - eth.getBlock(blockNum - sampleSize).timestamp) / sampleSize;
    difficulty = eth.getBlock(blockNum).difficulty; // You can sum up the last n-blocks and average; this is mathematically sound.

    return {
      "blocktime": blockTime,
      "difficulty": difficulty,
      "hashrate": difficulty / blockTime,
    };
}

Values are in seconds, hashes, and hashes per second, respectively.

Answer 2

I have implemented the above method with python, and it feels about the same as the computing power of the whole network hashrate!

eth = create_rpc("ETH")
current_height = int(eth.eth_blockNumber(), 16)
sampleSize = 200
current_block = eth.eth_getBlockByNumber(hex(current_height), False)
pre_height = eth.eth_getBlockByNumber(hex(current_height - sampleSize), False)
current_height_time = int(current_block.get("timestamp"), 16)
pre_height_time = int(pre_height.get("timestamp"), 16)

avg_block_time = (current_height_time - pre_height_time) / sampleSize
print(int(current_block.get("difficulty"), 16) / avg_block_time / 1000000000000)


result: 
177.7550919625694