Deep learning from Andrew Ng, recommended
link to youtube tutorial
Everyday R Code (19) – A function example to compare loops and vectorization speed
#to compare speed of 2 methods: loops and vectorization n=10 #generate 100 numbers between 1 and 1000, and then make a 10 by 10 matrix […]
Everyday R Code (18) – matrix calculation
Calculation1 Subtract different value from multiple columns b <- matrix(rep(1:20), nrow=4, ncol=5) c <- c(1,2,4) b c for(i in 1:nrow(b)) { b[i,3:5] <- b[i,3:5] […]
Interview：Concordant, Discordant and Tied Pairs for model validation
What are Concordant, Discordant and Tied Pairs for model validation? A friend who was interviewed by Amazon for a data related position was asked about […]
Everyday R code (17) Pivot table in R to replace excel
Pivot table in R to replace excel Step1 #converting data format using data.table library(data.table) live<-data.table(live) Step2 #finding unique count for each bucket using […]
Everyday SQL (7)
There are many interesting usage of sql function, like case when which is super powerful. Hope you can find something interesting or useful from the […]
Everyday SQL (6)
这是我工作遇到的问题，从别的组里要来了一堆SQL code，大概是四五年前在那工作的人写的，感觉是old style，之前从没见过，贴出来给大家。 Q: What’s the meaning of (+) in SQL queries (Oracle)? A: It’s Oracle’s synonym for OUTER JOIN. Example： SELECT * […]
Spyder did not work any more from Anaconda (02/18/2017). Here is the solution.
My spyder did not work any more from Anaconda. Here is the solution based on this post. Open your Terminal and use the command below. […]
latest procedure to install python and packages (Jan.27, 2017)
Happy Chinese New Year! I have to use a search tool to get information and it’s complicated. I need python to finish this task. (I […]
Python question list
if we have probability for each value, how to see the value’s distribution? We can use histgram to see the possible pdf (probability density function) […]