Re: How to efficiently resolve Associative Arrays not being sorted?
On 6/2/20 3:32 AM, BoQsc wrote:
I want to read a file, put it into an array, make some search and
replace on the content and output the modified text. However Associative
Arrays seem to be unsorted by default. Should I drop the Associative
Arrays and use something else? What are the ways to resolve this
randomness in Associative Arrays?
ReadfileAndCopyContentIntoArray.d
import std.stdio;
int lineNumber = 0;
char[][int] fileInArray;
void main(){
File exampleFile = File("exampleText.txt");
foreach(line; exampleFile.byLine){
lineNumber++;
fileInArray[lineNumber] ~= line;
}
writeln(fileInArray);
}
I have to ask because I don't know if this is similar to your true use
case or not -- but why would you use an AA when you have an ordered list
with keys that go from 0 to N? Why not just use an array?
As others have said, RedBlackTree can be used as an ordered map (though
this requires some definition of a mapping on top of it).
-Steve
Re: How to efficiently resolve Associative Arrays not being sorted?
On 6/2/20 12:32 AM, BoQsc wrote:
> I want to read a file, put it into an array, make some search and
> replace on the content and output the modified text.
How large is the data? If it fits into memory, just read the whole
thing, update it, sort the keys, and then output like this:
import std.stdio;
import std.algorithm;
foreach (key; aa.keys.sort) {
writeln(key, aa[key]);
}
Of course, you can save the sorted array in a local variable as well if
you will use it again:
auto keys = aa.keys.sort;
One great thing about programs that read and write files is that unless
the data is so large that it does not fit into physical memory, you
can't feel the time cost of that sort operation. :)
Ali
Re: How to efficiently resolve Associative Arrays not being sorted?
On Tuesday, 2 June 2020 at 07:32:56 UTC, BoQsc wrote:
I want to read a file, put it into an array, make some search
and replace on the content and output the modified text.
However Associative Arrays seem to be unsorted by default.
Should I drop the Associative Arrays and use something else?
What are the ways to resolve this randomness in Associative
Arrays?
ReadfileAndCopyContentIntoArray.d
import std.stdio;
int lineNumber = 0;
char[][int] fileInArray;
void main(){
File exampleFile = File("exampleText.txt");
foreach(line; exampleFile.byLine){
lineNumber++;
fileInArray[lineNumber] ~= line;
}
writeln(fileInArray);
}
exampleText.txt
The quick brown fox jumps over the lazy dog
Sphinx of black quartz, judge my vow.
How vexingly quick daft zebras jump!
The five boxing wizards jump quickly
Maecenas consectetur risus a lacus sodales iaculis.
Morbi sed tortor sollicitudin, pharetra massa egestas, congue
massa.
Sed sit amet nisi at ligula ultrices posuere quis nec est.
Mauris vel purus viverra, pellentesque elit id, consequat
felis.
The Command Prompt Output
[6:"Morbi sed tortor sollicitudin, pharetra massa egestas,
congue massa.\r", 7:"Sed sit amet nisi at ligula ultrices pos
uere quis nec est.\r", 2:"Sphinx of black quartz, judge my
vow.\r", 3:"How vexingly quick daft zebras jump!\r", 1:"The q
uick brown fox jumps over the lazy dog\r", 8:"Mauris vel purus
viverra, pellentesque elit id, consequat felis.", 5:"Maec
enas consectetur risus a lacus sodales iaculis.\r", 4:"The
five boxing wizards jump quickly\r"]
As can be seen in the Command Prompt Output, the array is not
ordered correctly.
It goes: 6: 7: 2: 3: 1: 8: 5: 4:
Instead of 1: 2: 3: 4: 5: 6: 7: 8:
Associative arrays looks that uses internally a hash map. Hash
maps are unordered. The ouput order, looks that is the result of
where the hash algorithm it's inserting the key/value pair in the
hashmap.
If you need order, you need to use a TreeMap (D std lib,
emsi_containers and containersd have TreeMap implementations) or
something like Java LinkedHashMap if order by insertion it's
enough.
How to efficiently resolve Associative Arrays not being sorted?
I want to read a file, put it into an array, make some search and
replace on the content and output the modified text. However
Associative Arrays seem to be unsorted by default. Should I drop
the Associative Arrays and use something else? What are the ways
to resolve this randomness in Associative Arrays?
ReadfileAndCopyContentIntoArray.d
import std.stdio;
int lineNumber = 0;
char[][int] fileInArray;
void main(){
File exampleFile = File("exampleText.txt");
foreach(line; exampleFile.byLine){
lineNumber++;
fileInArray[lineNumber] ~= line;
}
writeln(fileInArray);
}
exampleText.txt
The quick brown fox jumps over the lazy dog
Sphinx of black quartz, judge my vow.
How vexingly quick daft zebras jump!
The five boxing wizards jump quickly
Maecenas consectetur risus a lacus sodales iaculis.
Morbi sed tortor sollicitudin, pharetra massa egestas, congue
massa.
Sed sit amet nisi at ligula ultrices posuere quis nec est.
Mauris vel purus viverra, pellentesque elit id, consequat felis.
The Command Prompt Output
[6:"Morbi sed tortor sollicitudin, pharetra massa egestas,
congue massa.\r", 7:"Sed sit amet nisi at ligula ultrices pos
uere quis nec est.\r", 2:"Sphinx of black quartz, judge my
vow.\r", 3:"How vexingly quick daft zebras jump!\r", 1:"The q
uick brown fox jumps over the lazy dog\r", 8:"Mauris vel purus
viverra, pellentesque elit id, consequat felis.", 5:"Maec
enas consectetur risus a lacus sodales iaculis.\r", 4:"The five
boxing wizards jump quickly\r"]
As can be seen in the Command Prompt Output, the array is not
ordered correctly.
It goes: 6: 7: 2: 3: 1: 8: 5: 4:
Instead of 1: 2: 3: 4: 5: 6: 7: 8:
