Moritz Lennert wrote:
> I've finally gotten around to continue working on the d.thematic.*
> modules, and more specifically on the classification code. As mentioned
> earlier, I think it makes sense to make the latter into a library, so I
> decided to create lib_arraystats which contains functions for collecting
> basic statistics and for finding class breaks in arrays of doubles. In
> the future this could be filled with more statistical functions on such
> arrays.
>
> Could the gurus please have a look and tell me if the attached files are
> decent enough (except for the lacking documentation) to be committed to
> svn for further development ? Once that's done, I can also commit the
> d.thematic.area and v.class modules.
class_stdev() should probably just return the scale rather than a
formatted message. The caller can then construct the message if it so
desires.
Some stylistic comments:
1. "x += k", "x -= k" etc are clearer than "x = x + k" etc. The former
make it immediately clear that the variable (or array element, etc) is
being modified according to a particular idiom (i.e. having some
quantity added to or subtracted from it), rather than being assigned
the result of some arbitrary expression.
2. class_discont() looks like it might be more clear using an array of
structures for num/no/zz/co, rather than parallel arrays. E.g.
struct class {
int num;
double no;
double zz;
double co;
} *classes;
Then, code which accesses multiple fields doesn't need to keep
specifying the index. E.g.
for (j = 1; j <= i; j++) {
no[j] = num[j];
zz[j] = x[num[j]] * rangemax + min;
if (j == i)
continue;
if (co[j] > co[j + 1]) {
zz[j] = zz[j] + rangemin;
continue;
}
zz[j] = zz[j] - rangemin;
no[j] = no[j] - 1;
}
becomes:
for (j = 1; j <= i; j++) {
struct class *c = &classes[j];
struct class *next = &classes[j + 1];
c->no = c->num;
c->zz = x[c->num] * rangemax + min;
if (j == i)
continue;
if (c->co > next->co) {
c->zz += rangemin;
continue;
}
c->zz -= rangemin;
c->no -= 1;
}
The relieves the reader of the need to visually check all of those
[j]s to ensure that there isn't an [i] hidden amongst them.
--
Glynn Clements <[EMAIL PROTECTED]>
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