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Javascript reduce on array of objects
... the sum of the x properties of the parameters:
var arr = [{x:1},{x:2},{x:4}];
arr.reduce(function (a, b) {
return {x: a.x + b.x}; // returns object with property x
})
// ES6
arr.reduce((a, b) => ({x: a.x + b.x}));
// -> {x: 7}
Explanation added from comments:
The return value of each...
How do I use floating-point division in bash?
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248
You can't. bash only does integers; you must delegate to a tool such as bc.
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Use of def, val, and var in scala
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edited Apr 17 '11 at 4:46
Ying
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answered Dec 14 '10 at 15:...
How do you reverse a string in place in JavaScript?
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answered Jun 6 '09 at 4:34
belacquabelacqua
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Call apply-like function on each row of dataframe with multiple arguments from each row
...y to a subset of the original data.
dat <- data.frame(x=c(1,2), y=c(3,4), z=c(5,6))
apply(dat[,c('x','z')], 1, function(x) sum(x) )
or if your function is just sum use the vectorized version:
rowSums(dat[,c('x','z')])
[1] 6 8
If you want to use testFunc
testFunc <- function(a, b) a +...
YYYY-MM-DD format date in shell script
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In bash (>=4.2) it is preferable to use printf's built-in date formatter (part of bash) rather than the external date (usually GNU date).
As such:
# put current date as yyyy-mm-dd in $date
# -1 -> explicit current date, bash >=4...
Get generic type of class at runtime
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answered Aug 4 '10 at 8:55
HenningHenning
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Using git, how do I ignore a file in one branch but have it committed in another branch?
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84
This solution appears to work only for certain, patched versions of git. See a new answer poi...
【BLE技术内幕】BLE技术揭秘 - 创客硬件开发 - 清泛IT论坛，有思想、有深度
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BLE是低功耗蓝牙的英文缩写（Bluetooth Low Energy），是蓝牙4.0版本起开始支持的新的、低功耗版本的蓝牙技术规范。蓝牙技术联盟（Bluetooth SIG）在2010年发布了跨时代的蓝牙4.0，它并不是蓝牙3.0的简单升级版本，而是全新的技术架...
How do I compare two strings in Perl?
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answered Jul 24 '09 at 1:34
Sinan ÜnürSinan Ünür
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