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How can I get the intersection, union, and subset of arrays in Ruby?
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155
Utilizing the fact that you can do set operations on arrays by doing &(intersection), -(di...
How to get subarray from array?
I have var ar = [1, 2, 3, 4, 5] and want some function getSubarray(array, fromIndex, toIndex) , that result of call getSubarray(ar, 1, 3) is new array [2, 3, 4] .
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How to swap keys and values in a hash
...was inverted (in essence, by letting you access keys through values):
{a: 1, b: 2, c: 3}.key(1)
=> :a
If you want to keep the inverted hash, then Hash#invert should work for most situations:
{a: 1, b: 2, c: 3}.invert
=> {1=>:a, 2=>:b, 3=>:c}
BUT...
If you have duplicate values,...
Version of SQLite used in Android?
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UPDATE OCT 2016: Here is a link to the updated official docs which includes the main points in this answer: android.database.sqlite package-level javadoc
Using the emulators:
adb shell sqlite3 --version
UPDATE: Since SDK 29 (emulator ...
With bash, how can I pipe standard error into another process?
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172
There is also process substitution. Which makes a process substitute for a file.
You can send...
How to group dataframe rows into list in pandas groupby?
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12 Answers
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dplyr summarise: Equivalent of “.drop=FALSE” to keep groups with zero length in output
...e .drop argument that does just what you asked for:
df = data.frame(a=rep(1:3,4), b=rep(1:2,6))
df$b = factor(df$b, levels=1:3)
df %>%
group_by(b, .drop=FALSE) %>%
summarise(count_a=length(a))
#> # A tibble: 3 x 2
#> b count_a
#> <fct> <int>
#> 1 1 ...
LINQ where vs takewhile
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159
TakeWhile stops when the condition is false, Where continues and find all elements matching th...
Algorithm for Determining Tic Tac Toe Game Over
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133
You know a winning move can only happen after X or O has made their most recent move, so you c...
Could not find com.google.android.gms:play-services:3.1.59 3.2.25 4.0.30 4.1.32 4.2.40 4.2.42 4.3.23
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