qeatzy-优快云博客

原创 java pieces,

What is the difference between == vs equals() in Java?, Always remember to override hashCode if you override equals so as not to “break the contract”.equals will only compare what it is written to comp

2016-05-17 22:32:40 664

原创 python in learning math

limit behavior of transition probability of a given markov chain>>> import numpy as np>>> np.set_printoptions(precision=4)>>> g = lambda trans_mat, cnt=20: reduce(lambda x1, x2: print(x1) or x1@x2, (

2016-05-10 19:42:48 352

原创 pydata

numpyx = np.arange(9.).reshape(3, 3)np.where(x>5)x[x>5] # often simple boolean indexing suffices, np.where is not neededpandaspath = 'ch02/usagov_bitly_data2012-03-16-1331923249.txt'records = [json

2016-05-03 21:43:38 544

原创 x pieces

Is integer multiplication really same speed as addition on modern CPU Why is division so much more complex than other arithmetic operations?

2016-04-25 17:29:08 297

原创 plotting pieces

plotting multivariate function in python/matlab/R

2016-04-23 10:19:10 111

原创 latex pieces

math equation multiline alignment minimize f0(x)=x21+x22f_0(x) = x_{1}^2 + x_2^2 subject to f1(x)=x1/(1+x22)f_1(x) = x_1/(1+x_2^2) h1(x)=(x1+x2)2h_1(x) = (x_1 + x_2)^2

2016-04-23 10:00:44 320

原创 markdown pieces

Blockquotes &ensp List items

2016-04-22 20:20:41 297

原创 dm pieces

stochastic gradient descent

2016-04-22 16:15:18 317

原创 math pieces

Jensens’s inequality f(EX) <= Ef(x) f(y+t(x-y)) <= f(y) + t*(f(x)-f(y))

2016-04-22 15:56:26 324

原创 R pieces

set.seed(seed, kind = NULL, normal.kind = NULL), the recommended way to specify seeds.

2016-04-22 11:54:22 315

原创 python pieces

create partial sum of sequence using generator. ref: def partial_sums(iterable): total = 0 for i in iterable: total += i yield total

2016-04-21 23:08:48 993

原创 differences in python 2 and python 3

differences in python 2 and 3

2016-04-21 20:33:34 277

原创 notes reading word smart for the GRE 2nd Edition

notes reading word smart for the GRE 2nd Edition

2015-10-22 21:25:47 485

原创 abbreviations in english reading, writing, saying

abbreviations in english

2015-09-25 18:58:19 622

原创 my understanding of (lower bound,upper bound) binary search, in C++, thanks to two post

If you understand the comments below, never will you make mistakes with binary search!

2015-08-01 14:35:30 916

原创 learn python, ref, diveintopython

Decide in your heart of hearts what really excites and challenges you, and start moving your life in that direction. Don't let life randomly kick you into the adult you don't want to become.

2015-07-22 14:42:57 599

原创 one recursive approach for 3, hdu 1016 (with an improved version) , permutations, N-Queens puzzle

one recursive approach to solve hdu 1016 , list all permutations, solve N-Queens puzzle. reference: the video of stanford cs106b lecture 10 by Julie Zelenski https://www.youtube.com/watch?v=NdF1QDTRkck

2015-07-19 16:49:37 698

原创 hdu 1503, LCS variants, find a LCS, not just the length, backtrack to find LCS, no extra markup

a typical variant of LCS algo. the key point here is, the dp[][] array contains enough message to determine the LCS, not only the length, but all of LCS candidates, we can backtrack to find all of LCS.

2015-07-18 16:24:57 785

原创 hdu, KMP algorithm, linear string search algorithm, a nice reference provided

Rabin-Karp and Knuth-Morris-Pratt Algorithms

2015-07-18 13:40:00 135

原创 hdu 1712, multiple-choice knapsack,

multiple-choice knapsack

2015-07-18 13:25:57 761

原创 hdu 1232, disjoint set, linked list vs. rooted tree, a minor but substantial optimization for path c

disjoint set, linked list version with weighted-union heuristic, rooted tree version with rank by union and path compression, and a minor but substantial optimization for path compression version FindSet.

2015-07-16 17:13:52 671