I have a strange problem. But first, I want to match a hierarchy-based string onto the value of a column in a pandas data frame and count the occurrence of the current node and all of its children.
| index | hierarchystr |
| ----- | --------------------- |
| 0 | level0level00level000|
| 1 | level0level01 |
| 2 | level0level02level021|
| 3 | level0level02level021|
| 4 | level0level02level020|
| 5 | level0level02level021|
| 6 | level1level02level021|
| 7 | level1level02level021|
| 8 | level1level02level021|
| 9 | level2level02level021|
Assume that there are 300k lines. Each node can have multiple children with again multiple children so on and so forth (here represented by level0-2 strings). Now I have a separate hierarchy where I extract the hierarchy strings from. Now to the problem:
#hstrs = ["level0", "level1", "level0level01", "level0level02", "level0level02level021"]
pat = "|".join(hstrs)
s = df.hierarchystr.str.extract('(' + pat + ')', expand=True)[0]
df1 = df.groupby(s).size().reset_index(name='Count')
df1 = df1[df1 > 200]
size = len(df1)
The size of the found matched substrings with occurrence greater than 200 differ every RUN! "level0" should match every row where the hierarchy str level0 is included and should build a group with all its subchildren and that size needs to be greater than 200.
Edit:// levelX is just an example, i have thousands of nodes, with different names and again thousands of different subchilds. The hstrs strings do not include each other, besides the parent nodes. (E.g. "parent1" is included in "parent1subchild1" and "parent1subchild2")
I traced it back to a different order of the hierarchy strings in the array hstrs. So I changed the code and compare each substring individually:
for hstr in hstrs:
s = df.hierarchystr.str.extract('(' + hstr + ')', expand=True)
s2 = s.count()
s3 = s2.values[0]
if s3 > 200:
list.append(hstr)
This is slow as hell, but the result sticks the same, no matter which order hstrs has. But for efficiency is it possible to do the same with only one regex matching group, all at once for all hstrs?
Edit://
expected output would be:
|index| 0 | Count |
|-----|---------------------|-------|
|0 |level0 | 5 |
|1 |level1 | 3 |
|2 |level0level01 | 1 |
|3 |level0level02 | 4 |
|4 |level0level02level021| 3 |
Edit2://
it has something to do with the ordering of hstrs. I think with the match and stop after the first match the behavior of the extract method. If the ordering is different the hierarchy strings in the pat will be matched differently which results in different sizes of each group. A high hierarchy (short str) will be matched first, the lower hierarchy levels in the same pat won't be matched again. But IDK what to do against this behavior.
Edit3://
an alternative would be, but is also slow as hell:
for hstr in hstrs:
s = df[df.hierarchystr.str.contains(fqn)]
s2 = s.count()
s3 = s2.values[0]
if s3 > 200:
beforeset.append(fqn)
Edit4://
I think what I am searching for is the opportunity to do a "group_by" with "contains" or "is in" for the hstrs. I am glad for every Idea. :)
Edit5://
Found a simple, but not satisfying alternative (but faster than the previous tries):
containing =[item for hierarchystr in df.hierarchystr for item in hstrs if item in hierarchystr]
containing = Counter(containing)
df1 = pd.DataFrame([containing]).T
nodeNamesWithOver200 = df1[df1 > 200].dropna().index.values
Related
as shown in the example below, the output of the query contains blockid startds from 324 and it ends at 127, hence, the itempointer or the row index within the block starts from one for each new block id. in otherwords, as shown below
for the blockid 324 it has only itempointer with index 10
for the blockid 325 it has itempointers starts with 1 and ends with 9
i want to have a single blockid so that the itempointer or the row index starts from 1 and ends with 25
plese let me know how to achive that and
why i have three different blockids?
ex-1
query:
select ctid
from awanti_grid_cell_data agcd
where selectedsiteid = '202230060950'
and centerPointsOfWindowAsGeoJSONInEPSG4326ForCellsInTreatment IS NOT NULL
and centerPointsOfWindowAsGeoJSONInEPSG4326ForCellsInTreatment <> 'None'
result:
|ctid |
|--------|
|(324,10)|
|(325,1) |
|(325,2) |
|(325,3) |
|(325,4) |
|(325,5) |
|(325,6) |
|(325,7) |
|(325,8) |
|(325,9) |
|(326,1) |
|(326,2) |
|(326,3) |
|(326,4) |
|(326,5) |
|(326,6) |
|(326,7) |
|(326,8) |
|(326,9) |
|(327,1) |
|(327,2) |
|(327,3) |
|(327,4) |
|(327,5) |
|(327,6) |
You are missing the point. The ctid is the physical address of a row in the table, and it is none of your business. The database is free to choose whatever place it thinks fit for a table row. As a comparison, you cannot go to the authorities and request that your social security number should be 12345678 - it is simply assigned to you, and you have no say. That's how it is with the physical location of tuples.
Very likely you are not asking this question out of pure curiosity, but because you want to solve some problem. You should instead ask a question about your real problem, and there may be a good answer to that. But whatever problem you are trying to solve, using the ctid is probably not the correct answer, in particular if you want to control it.
Table 1:
G H I J K
| Lane | Bowler | Score | Score | Score | 1
|:-----------|------------:|:------------:|:------------:|:------------:|
| Lane 1 | Thomas| 100 | 100 | 100 | 2
| Lane 2 | column | 200 | 200 | 100 | 3
| Lane 3 | Mary | 300 | 300 | 100 | 4
| Lane 1 | Cool | 150 | 400 | 100 | 5
| Lane 2 | right | 160 | 500 | 100 | 6
| Lane 9 | Susan | 170 | 600 | 100 | 7
say I want to find the average for each Lane that appeared in table 2 and put them in column O:
Table 2:
N O
| Lane | Average | 1
|:-----------|------------:|
| Lane 1 | | 2
| Lane 2 | | 3
| Lane 3 | | 4
I would put
=AVERAGE(IF(N2=$G$2:$G$7, $I$2:$K$7 )) for lane 1 (put this formula on cell "O2")
=AVERAGE(IF(N3=$G$2:$G$7, $I$2:$K$7 )) for Lane 2 ("O3")
=AVERAGE(IF(N4=$G$2:$G$7, $I$2:$K$7 )) for Lane 2 ("O4")
My first question is
What if I want to find the Average of ALL the lane together that appear in table 2. So average of Lane 1, Lane 2 and Lane 3 together (but not other lane, such as lane 9).
My attempt:
= Average(IF(G2:G7 = N2:N4, I2:K:7)) why doesn't this work?
My second question is
I have done the "average of each individual Lane" using vba:
.
Dim i As Integer
For i = 2 To 4
Cells(i, 15).FormulaArray = "=AVERAGE(IF(RC[-1]=R2C7:R7C7,R2C9:R7C12))"
Next i
.
What if I have done it using vba without the .formula method
For Lane 1 only:
pseudo code:
Loop from G2 to G7
If cell (N1) = Gx then //x: 2 to 7
Sum = Sum + Ix + Jx + Kx
}
Average = Sum/totalEntries
Would this be slower than if I were to use the build in .formula? is there a advanage to doing it this way instead?
The answer to the first question about why this FormulaArray
= Average(IF(G2:G7 = N2:N4, I2:K7)) doesn't work?
Is implicit on how this other FormulaArray works:
= AVERAGE( IF( $G$7:$G$12 = $N7, $I$7:$K$12 ) )
Let’s see how each part of this “single-cell formula array” works:
1st part: $G$7:$G$12 = $N7
The first part of the formula generates an array with the records from range $G$7:$G$12 complying with the condition = $N7. Fig. 1 shows the first part of the FormulaArray in as a “multi-cell formula array”.
2nd Part: $I$7:$K$12
The result of the first part is applied to the second part to obtain the range of scores complying with the condition = $N7 (see Fig. 2)
3rd part: AVERAGE
Finally the last part of the formula calculates the average of the scores complying with the condition = $N7
Now let’s try to apply the same analysis to the formula:
= AVERAGE( IF( G2:G7 = N2:N4, I2:K7 ) )
Unfortunately, we cannot go beyond the first part G2:G7 = N2:N4 as it fails trying to compare two arrays of different dimensions thus resulting in #N/A (see Fig. 3)
However, even if the arrays have same dimension the result would not have shown the duplicated values, as the members are compared one to one (see Fig. 4)
To obtain the average for Lanes 1 to 3 use this FormulaArray
=AVERAGE( IF(
( $G$7:$G$12 = $N7 ) + ( $G$7:$G$12 = $N8 ) + ( $G$7:$G$12 = $N9 ),
$I$7:$K$12 ) )
It generates an array with the records complying with the conditions = $N7 + = $N8 + = $N9 (+ equivalent to operator OR)
As regards the second question:
Performance is intrinsically associated to maintenance and efficiency.
The sample procedure just enters a formula which is hard coded and only works for this particular case, for example:
If needed to change the formulas to expand the ranges, the macro has to be updated, it may still have to change the formula but no need to open the VBA editor.
If any of the columns before column G get deleted as it becomes obsolete, the macro needs to be updated, while the formulas will not require any maintenance as they are automatically updated.
In reference to the macro without the .Formula method
I found this redundant, as it’s like writing an algorithm to do something that can be done efficiently and accurately with an existing function, as such a macro will not bring anything that's it's not there actually.
I'll consider the advantage of writing such a procedure in a situation in which the workbook is very large and it heavily uses resource significantly slowing down the performance of the workbook, however the advantages to be delivered by the procedure will not reside and just writing the formulas but it must calculate the results and enter the values resulting from the formulas instead of the formulas thus making the workbook light, fast and smooth to the end user.
To get the average of them all, just use
=AVERAGE(I2:K7)
As to the VBA, as it is all done on the same lines, could you just use
For i = 2 To 7
Cells(i,"O").Value = Application.Sum(Range(Cells(i,"I"),Cells(i,"K")))
Next i
I want to use the same labels from a SQLAlchemy table, to re-aggregate some data (e.g. I want to iterate through mytable.c to get the column names exactly).
I have some spending data that looks like the following:
| name | region | date | spending |
| John | A | .... | 123 |
| Jack | A | .... | 20 |
| Jill | B | .... | 240 |
I'm then passing it to an existing function we have, that aggregates spending over 2 periods (using a case statement) and groups by region:
grouped table:
| Region | Total (this period) | Total (last period) |
| A | 3048 | 1034 |
| B | 2058 | 900 |
The function returns a SQLAlchemy query object that I can then use subquery() on to re-query e.g.:
subquery = get_aggregated_data(original_table)
region_A_results = session.query(subquery).filter(subquery.c.region = 'A')
I want to then re-aggregate this subquery (summing every column that can be summed, replacing the region column with a string 'other'.
The problem is, if I iterate through subquery.c, I get labels that look like:
anon_1.region
anon_1.sum_this_period
anon_1.sum_last_period
Is there a way to get the textual label from a set of column objects, without the anon_1. prefix? Especially since I feel that the prefix may change depending on how SQLAlchemy decides to generate the query.
Split the name string and take the second part, and if you want to prepare for the chance that the name is not prefixed by the table name, put the code in a try - except block:
for col in subquery.c:
try:
print(col.name.split('.')[1])
except IndexError:
print(col.name)
Also, the result proxy (region_A_results) has a method keys which returns an a list of column names. Again, if you don't need the table names, you can easily get rid of them.
We use Lucene.net for indexing. One of the fields that we index, is a numeric field with the values 1 to 6 and 9999 for not set.
When using Luke to explore the index, we see terms that we do not recognize. The index contains a total of 38673 documents, and Luke shows the following top ranked terms for this field:
Term | Rank | Field | Text | Text (decoded as numeric-int)
1 | 38673 | Axis | x | 0
2 | 38673 | Axis | p | 0
3 | 38673 | Axis | t | 0
4 | 38673 | Axis | | | 0
5 | 19421 | Axis | l | 0
6 | 19421 | Axis | h | 0
7 | 19421 | Axis | d# | 0
8 | 19252 | Axis | ` N | 9999
9 | 19252 | Axis | l | 8192
10 | 19252 | Axis | h ' | 9984
11 | 19252 | Axis | d# p | 9984
12 | 18209 | Axis | ` | 4
13 | 950 | Axis | ` | 1
14 | 116 | Axis | ` | 5
15 | 102 | Axis | ` | 6
16 | 26 | Axis | ` | 3
17 | 18 | Axis | ` | 2
We find the same pattern for other numeric fields.
Where does the unknown values come from?
NumericFields are indexed using a trie structure. The terms you see are part of it, but will not return results if you query for them.
Try indexing your NumericField with a precision step of Int32.MaxValue and the values will go away.
NumericField documentation
... Within Lucene, each numeric value is indexed as a trie structure, where each term is logically assigned to larger and larger pre-defined brackets (which are simply lower-precision representations of the value). The step size between each successive bracket is called the precisionStep, measured in bits. Smaller precisionStep values result in larger number of brackets, which consumes more disk space in the index but may result in faster range search performance. The default value, 4, was selected for a reasonable tradeoff of disk space consumption versus performance. You can use the expert constructor NumericField(String,int,Field.Store,boolean) if you'd like to change the value. Note that you must also specify a congruent value when creating NumericRangeQuery or NumericRangeFilter. For low cardinality fields larger precision steps are good. If the cardinality is < 100, it is fair to use Integer.MAX_VALUE, which produces one term per value. ...
More details on the precision step available in the NumericRangeQuery documentation:
Good values for precisionStep are depending on usage and data type:
• The default for all data types is 4, which is used, when no
precisionStep is given.
• Ideal value in most cases for 64 bit data
types (long, double) is 6 or 8.
• Ideal value in most cases for 32 bit
data types (int, float) is 4.
• For low cardinality fields larger
precision steps are good. If the cardinality is < 100, it is fair to use •Integer.MAX_VALUE (see below).
• Steps ≥64 for long/double and
≥32 for int/float produces one token per value in the index and
querying is as slow as a conventional TermRangeQuery. But it can be
used to produce fields, that are solely used for sorting (in this case
simply use Integer.MAX_VALUE as precisionStep). Using NumericFields
for sorting is ideal, because building the field cache is much faster
than with text-only numbers. These fields have one term per value and
therefore also work with term enumeration for building distinct lists
(e.g. facets / preselected values to search for). Sorting is also
possible with range query optimized fields using one of the above
precisionSteps.
EDIT
little sample, the index produced by this will show terms with value 8192, 9984, 1792, etc in luke, but using a range that would include them in the query doesnt produce results:
NumericField number = new NumericField("number", Field.Store.YES, true);
Field regular = new Field("normal", "", Field.Store.YES, Field.Index.ANALYZED);
IndexWriter iw = new IndexWriter(FSDirectory.GetDirectory("C:\\temp\\testnum"), new StandardAnalyzer(), true);
Document doc = new Document();
doc.Add(number);
doc.Add(regular);
number.SetIntValue(1);
regular.SetValue("one");
iw.AddDocument(doc);
number.SetIntValue(2);
regular.SetValue("one");
iw.AddDocument(doc);
number.SetIntValue(13);
regular.SetValue("one");
iw.AddDocument(doc);
number.SetIntValue(2000);
regular.SetValue("one");
iw.AddDocument(doc);
number.SetIntValue(9999);
regular.SetValue("one");
iw.AddDocument(doc);
iw.Commit();
IndexSearcher searcher = new IndexSearcher(iw.GetReader());
NumericRangeQuery rangeQ = NumericRangeQuery.NewIntRange("number", 1, 2, true, true);
var docs = searcher.Search(rangeQ);
Console.WriteLine(docs.Length().ToString()); // prints 2
rangeQ = NumericRangeQuery.NewIntRange("number", 13, 13, true, true);
docs = searcher.Search(rangeQ);
Console.WriteLine(docs.Length().ToString()); // prints 1
rangeQ = NumericRangeQuery.NewIntRange("number", 9000, 9998, true, true);
docs = searcher.Search(rangeQ);
Console.WriteLine(docs.Length().ToString()); // prints 0
Console.ReadLine();
I want to represent the list "hi", "hello", "goodbye", "good day", "howdy" (with that order), in a SQL table:
pk | i | val
------------
1 | 0 | hi
0 | 2 | hello
2 | 3 | goodbye
3 | 4 | good day
5 | 6 | howdy
'pk' is the primary key column. Disregard its values.
'i' is the "index" that defines that order of the values in the 'val' column. It is only used to establish the order and the values are otherwise unimportant.
The problem I'm having is with inserting values into the list while maintaining the order. For example, if I want to insert "hey" and I want it to appear between "hello" and "goodbye", then I have to shift the 'i' values of "goodbye" and "good day" (but preferably not "howdy") to make room for the new entry.
So, is there a standard SQL pattern to do the shift operation, but only shift the elements that are necessary? (Note that a simple "UPDATE table SET i=i+1 WHERE i>=3" doesn't work, because it violates the uniqueness constraint on 'i', and also it updates the "howdy" row unnecessarily.)
Or, is there a better way to represent the ordered list? I suppose you could make 'i' a floating point value and choose values between, but then you have to have a separate rebalancing operation when no such value exists.
Or, is there some standard algorithm for generating string values between arbitrary other strings, if I were to make 'i' a varchar?
Or should I just represent it as a linked list? I was avoiding that because I'd like to also be able to do a SELECT .. ORDER BY to get all the elements in order.
As i read your post, I kept thinking 'linked list'
and at the end, I still think that's the way to go.
If you are using Oracle, and the linked list is a separate table (or even the same table with a self referencing id - which i would avoid) then you can use a CONNECT BY query and the pseudo-column LEVEL to determine sort order.
You can easily achieve this by using a cascading trigger that updates any 'index' entry equal to the new one on the insert/update operation to the index value +1. This will cascade through all rows until the first gap stops the cascade - see the second example in this blog entry for a PostgreSQL implementation.
This approach should work independent of the RDBMS used, provided it offers support for triggers to fire before an update/insert. It basically does what you'd do if you implemented your desired behavior in code (increase all following index values until you encounter a gap), but in a simpler and more effective way.
Alternatively, if you can live with a restriction to SQL Server, check the hierarchyid type. While mainly geared at defining nested hierarchies, you can use it for flat ordering as well. It somewhat resembles your approach using floats, as it allows insertion between two positions by assigning fractional values, thus avoiding the need to update other entries.
If you don't use numbers, but Strings, you may have a table:
pk | i | val
------------
1 | a0 | hi
0 | a2 | hello
2 | a3 | goodbye
3 | b | good day
5 | b1 | howdy
You may insert a4 between a3 and b, a21 between a2 and a3, a1 between a0 and a2 and so on. You would need a clever function, to generate an i for new value v between p and n, and the index can become longer and longer, or you need a big rebalancing from time to time.
Another approach could be, to implement a (double-)linked-list in the table, where you don't save indexes, but links to previous and next, which would mean, that you normally have to update 1-2 elements:
pk | prev | val
------------
1 | 0 | hi
0 | 1 | hello
2 | 0 | goodbye
3 | 2 | good day
5 | 3 | howdy
hey between hello & goodbye:
hey get's pk 6,
pk | prev | val
------------
1 | 0 | hi
0 | 1 | hello
6 | 0 | hi <- ins
2 | 6 | goodbye <- upd
3 | 2 | good day
5 | 3 | howdy
the previous element would be hello with pk=0, and goodbye, which linked to hello by now has to link to hey in future.
But I don't know, if it is possible to find a 'order by' mechanism for many db-implementations.
Since I had a similar problem, here is a very simple solution:
Make your i column floats, but insert integer values for the initial data:
pk | i | val
------------
1 | 0.0 | hi
0 | 2.0 | hello
2 | 3.0 | goodbye
3 | 4.0 | good day
5 | 6.0 | howdy
Then, if you want to insert something in between, just compute a float value in the middle between the two surrounding values:
pk | i | val
------------
1 | 0.0 | hi
0 | 2.0 | hello
2 | 3.0 | goodbye
3 | 4.0 | good day
5 | 6.0 | howdy
6 | 2.5 | hey
This way the number of inserts between the same two values is limited to the resolution of float values but for almost all cases that should be more than sufficient.