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print("hello world!")| """example of converting a numpy array to a C++ valarray and back in cython | |
| using copies. | |
| Compile with `python setup.py build_ext --inplace` | |
| Example | |
| ------- | |
| >>> import cpptest, numpy as np | |
| >>> x = np.array([0., 1., 2.]) |
| # make sure you have these installed | |
| yum install -y make gcc perl pcre-devel zlib-devel |
| import requests | |
| data = requests.get('http://api.wunderground.com/api/INSERT_KEY_HERE/geolookup/conditions/q/Switzerland/Zurich.json').json() | |
| location = data['location']['city'] | |
| temp_c = data['current_observation']['temp_c'] | |
| print "Current temperature in %s is: %s C" % (location, temp_c) |
Located in alphabetical order (not prefer)
Cab), also designed as a more modern replacement, written in Cgolang)| -- show running queries (pre 9.2) | |
| SELECT procpid, age(clock_timestamp(), query_start), usename, current_query | |
| FROM pg_stat_activity | |
| WHERE current_query != '<IDLE>' AND current_query NOT ILIKE '%pg_stat_activity%' | |
| ORDER BY query_start desc; | |
| -- show running queries (9.2) | |
| SELECT pid, age(clock_timestamp(), query_start), usename, query | |
| FROM pg_stat_activity | |
| WHERE query != '<IDLE>' AND query NOT ILIKE '%pg_stat_activity%' |
L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns
Compress 1K bytes with Zippy ............. 3,000 ns = 3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns = 20 µs
SSD random read ........................ 150,000 ns = 150 µs
Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs
| Latency Comparison Numbers (~2012) | |
| ---------------------------------- | |
| L1 cache reference 0.5 ns | |
| Branch mispredict 5 ns | |
| L2 cache reference 7 ns 14x L1 cache | |
| Mutex lock/unlock 25 ns | |
| Main memory reference 100 ns 20x L2 cache, 200x L1 cache | |
| Compress 1K bytes with Zippy 3,000 ns 3 us | |
| Send 1K bytes over 1 Gbps network 10,000 ns 10 us | |
| Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD |