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Replacing NAs with latest non-NA value
...'a',NA,NA,NA,NA,NA,NA,NA,NA,'b','c','d',NA,NA,NA,NA,NA,'e')
xx = rep(x, 1000000)
system.time({ yzoo = na.locf(xx,na.rm=F)})
## user system elapsed
## 2.754 0.667 3.406
system.time({ yrep = repeat.before(xx)})
## user system elapsed
## 0.597 0.199 0.793
Edit
As this b...
二维码的生成细节及原理 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...数字分成三组: 012 345 67
2. 把他们转成二进制: 012 转成 0000001100； 345 转成 0101011001； 67 转成 1000011。
3. 把这三个二进制串起来: 0000001100 0101011001 1000011
4. 把数字的个数转成二进制 (version 1-H是10 bits ): 8个数字的二进制是 000000100...
Why is the minimalist, example Haskell quicksort not a “true” quicksort?
...plexity of the original algorithm. Not even close. That's why it is over 1,000x slower than Sedgewick's genuine Quicksort in C.
– J D
May 27 '16 at 17:34
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...
Creating multiline strings in JavaScript
...ing value of a string literal is to use an escape sequence such as \n or \u000A."
– some
Sep 25 '12 at 2:28
17
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JavaScript data grid for millions of rows [closed]
...nce in performance between working with a grid with 10 rows versus a 100’000 rows."
Some highlights:
Adaptive virtual scrolling (handle hundreds of thousands of rows)
Extremely fast rendering speed
Background post-rendering for richer cells
Configurable & customizable
Full keyboard navigati...
How to get a complete list of ticker symbols from Yahoo Finance? [closed]
... }
}
}
It gave me a list of about 75,000 securities in about 4 mins.
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jQuery table sort
...y, you don't mention how many rows we're talking about here.
If you pass 5000 lines to the browser from the database, knowing that the actual database-table contains 100,000 rows, my question is: what's the point in making the table sortable? In order to do a proper sort, you'd have to send the qu...
.toArray(new MyClass[0]) or .toArray(new MyClass[myList.size()])?
...00 avgt 30 0.155 ▒ 0.004 us/op
c.a.p.SO29378922.preSize 1000 avgt 30 1.512 ▒ 0.031 us/op
c.a.p.SO29378922.preSize 5000 avgt 30 6.884 ▒ 0.130 us/op
c.a.p.SO29378922.preSize 10000 avgt 30 13.147 ▒ 0.199 us/op
c.a.p.SO29378922.preSize ...
Django - limiting query results
...ler())
In [23]: User.objects.all().order_by('-id')[:10]
(0.000) SELECT "auth_user"."id", "auth_user"."username", "auth_user"."first_name", "auth_user"."last_name", "auth_user"."email", "auth_user"."password", "auth_user"."is_staff", "auth_user"."is_active", "auth_user"."is_superuser"...
Hex representation of a color with alpha channel?
...reprocessor like SASS then you can pass an hex to rgba:
background:
rgba(#000, 0.5);
And the preprocessor just converts the hex code to rgb automatically.
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