大约有 10,000 项符合查询结果（耗时：0.0188秒） [XML]
What's the fastest way to read a text file line-by-line?
...xcept that this method grows a list of strings used to create the returned array of lines so the memory requirements are higher. However, it returns String[] and not an IEnumerable<String> allowing you to randomly access the lines.
var lines = File.ReadAllLines(fileName);
for (var i = 0; i &l...
Very large matrices using Python and NumPy
...nd. Not bad for a Python-based solution!
Accessing the data as a NumPy recarray again is as simple as:
data = table[row_from:row_to]
The HDF library takes care of reading in the relevant chunks of data and converting to NumPy.
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Modifying a subset of rows in a pandas dataframe
...c here, .loc is primarily label based, but may also be used with a boolean array.
So, what we are doing above is applying df.loc[row_index, column_index] by:
Exploiting the fact that loc can take a boolean array as a mask that tells pandas which subset of rows we want to change in row_index
Ex...
What is the difference between sed and awk? [closed]
...ramming constructs including if/else, while, do/while and for (C-style and array iteration). There is complete support for variables and single-dimension associative arrays plus (IMO) kludgey multi-dimension arrays. Mathematical operations resemble those in C. It has printf and functions. The "K" in...
What is the most accurate way to retrieve a user's correct IP address in PHP?
...cleaner way to get the IP address:
function get_ip_address(){
foreach (array('HTTP_CLIENT_IP', 'HTTP_X_FORWARDED_FOR', 'HTTP_X_FORWARDED', 'HTTP_X_CLUSTER_CLIENT_IP', 'HTTP_FORWARDED_FOR', 'HTTP_FORWARDED', 'REMOTE_ADDR') as $key){
if (array_key_exists($key, $_SERVER) === true){
...
convert ArrayList to JSONArray
I have an ArrayList that I use within an ArrayAdapter for a ListView. I need to take the items in the list and convert them to a JSONArray to send to an API. I've searched around, but haven't found anything that explains how this might work, any help would be appreciated.
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How do I check if a given string is a legal/valid file name under Windows?
...expression.
UPD2: Note that according to the Remarks section in MSDN "The array returned from this method is not guaranteed to contain the complete set of characters that are invalid in file and directory names." The answer provided by sixlettervaliables goes into more details.
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Apache Spark: map vs mapPartitions?
...lephant"), 3)
val b = a.map(_.length)
val c = a.zip(b)
c.collect
res0: Array[(String, Int)] = Array((dog,3), (salmon,6), (salmon,6), (rat,3), (elephant,8))
mapPartitions
This is a specialized map that is called only once for each partition.
The entire content of the respective partition...
Apply formula to the entire column
...lumn data first and only apply your formula to one. The above answer with "ArrayFormula" seems to be able to apply a many cells to one formula, which is not what OP wanted.
– Thanasis Kapelonis
May 3 '16 at 18:03
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What are the lesser known but useful data structures?
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Bloom filter: Bit array of m bits, initially all set to 0.
To add an item you run it through k hash functions that will give you k indices in the array which you then set to 1.
To check if an item is in the set, compute the k indices and c...