大约有 44,000 项符合查询结果（耗时：0.0248秒） [XML]
Join vs. sub-query
...rence to the upper query, especially when it comes to row-counts above 100,000. The thing seems to be memory usage and paging to the swap-file. A join would produce a very big amount of data, that may not fit into memory and must be paged into the swap-file. Whenever this is the case the query-times...
How do I get currency exchange rates via an API such as Google Finance? [closed]
...%22USDCHF%22%29
Open Source Exchange Rates API
Free for personal use (1000 hits per month)
Changing "base" (from "USD") is not allowed in Free account
Requires registration.
Request: http://openexchangerates.org/latest.json
Response:
<!-- language: lang-js -->
{
"disclaimer":...
Why no ICloneable?
... 'real world' that also does something other than implement it (in the ~60,000 apps that we have access to).
Now if you would just like to enforce a pattern that you want your 'cloneable' objects to implement, that's a completely fine usage - and go ahead. You can also decide on exactly what "cloni...
Pandas: create two new columns in a dataframe with values calculated from a pre-existing column
... also much faster on larger DataFrames
df = pd.DataFrame({'a': [1,2,3] * 100000, 'b': [2,3,4] * 100000})
DataFrame created with 300,000 rows
%timeit df["A1"], df["A2"] = calculate(df['a'])
2.65 ms ± 92.4 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)
%timeit df["A1"], df["A2"] = zi...
What is the Invariant Culture?
...mmers which think the word is english ;) And then german customers write 1.000,00 for 1000 ;) Ouch. * Even in the same language, Switzerland and Germany for example use "." and "," in different ways in numbers. Result -> Config files are garbage. Use Invariant Language there ;)
...
String output: format or concat in C#?
...ded the result by some iterations was wrong. See what happens if you have 1000 milliseconds and 100 milliseconds. In both situations, you will get 0 ms after dividing it by 1000000.
Stopwatch s = new Stopwatch();
var p = new { FirstName = "Bill", LastName = "Gates" };
int n = 1000000;
long fElaps...
What can MATLAB do that R cannot do? [closed]
...operations).
R has statistical functionality hard to find elsewhere (>2000 Packages on CRAN), and lots of statisticians use it. On the other hand, MATLAB has lots of (expensive) toolboxes for engineering applications like
image processing/image acquisition,
filter design,
fuzzy logic/fuzzy con...
C# switch statement limitations - why?
...le use if they aren't:
case 10: blah; break;
case 200: blah; break;
case 3000: blah; break;
(You'd need a table ~3000 entries in size, with only 3 slots used)
With non-adjacent expressions, the compiler may start to perform linear if-else-if-else checks.
With larger non- adjacent expression set...
Android - shadow on text?
...textSize">12sp</item>
<item name="android:shadowColor">#000000</item>
<item name="android:shadowDx">1</item>
<item name="android:shadowDy">1</item>
<item name="android:shadowRadius">1</item>
</style>
And in your layou...
How to loop through array in jQuery?
...5 elements in total but their indexes are strewn across the range 0 to 150,000 for some reason, and so the length is 150,001), and if you use appropriate safeguards like hasOwnProperty and checking the property name is really numeric (see link above), for..in can be a perfectly reasonable way to avo...