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Average of 3 long integers
...ides all three values (it floors the values, so you 'lose' the remainder), and then divides the remainder:
long n = x / 3
+ y / 3
+ z / 3
+ ( x % 3
+ y % 3
+ z % 3
) / 3
Note that the above sample does not always work properly when h...
Rename specific column(s) in pandas
...' else x for x in df.columns]
Or, construct a mapping using a dictionary and perform the list-comprehension with it's get operation by setting default value as the old name:
col_dict = {'gdp': 'log(gdp)', 'cap': 'cap_mod'} ## key→old name, value→new name
df.columns = [col_dict.get(x, x) fo...
Matplotlib scatter plot with different text at each data point
I am trying to make a scatter plot and annotate data points with different numbers from a list.
So, for example, I want to plot y vs x and annotate with corresponding numbers from n .
...
Pass a data.frame column name to a function
I'm trying to write a function to accept a data.frame ( x ) and a column from it. The function performs some calculations on x and later returns another data.frame. I'm stuck on the best-practices method to pass the column name to the function.
...
Why does Go have a “goto” statement
...nt. I've always been taught that 'goto' statements are a thing of the past and evil for it occludes the actual flow of a program, and that functions or methods are always a better way of controlling flow.
...
What encoding/code page is cmd.exe using?
...
Yes, it’s frustrating—sometimes type and other programs
print gibberish, and sometimes they do not.
First of all, Unicode characters will only display if the
current console font contains the characters. So use
a TrueType font like Lucida Console instead of the...
Simultaneously merge multiple data.frames in a list
... issue here is that each data.frame differs in terms of the number of rows and columns, but they all share the key variables (which I've called "var1" and "var2" in the code below). If the data.frames were identical in terms of columns, I could merely rbind , for which plyr's rbind.fill would...
Does the ternary operator exist in R?
...
As if is function in R and returns the latest evaluation, if-else is equivalent to ?:.
> a <- 1
> x <- if(a==1) 1 else 2
> x
[1] 1
> x <- if(a==2) 1 else 2
> x
[1] 2
The power of R is vectorization. The vectorization of t...
How to drop columns by name in a data frame
I have a large data set and I would like to read specific columns or drop all the others.
11 Answers
...
Fastest way to determine if an integer's square root is an integer
... ~35% faster than your 6bits+Carmack+sqrt code, at least with my CPU (x86) and programming language (C/C++). Your results may vary, especially because I don't know how the Java factor will play out.
My approach is threefold:
First, filter out obvious answers. This includes negative numbers and ...