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2. What does the group number mean on the periodic table of ... -...

   socratic.org/questions/what-does-the-group-number-mean-on-the-periodic-table...

   The group number in the periodic table represents number of valence electrons of the elements in a certain group. For example, all the elements in Group −1 have 1 electron in their outer most shell. The group number in the periodic table represents number of valence electrons of the elements in a certain group.

3. python - Pandas, groupby and count - Stack Overflow

   stackoverflow.com/questions/47320572

   To count the number of non-nan rows in a group for a specific column, check out the accepted answer. Old. df.groupby(['A', 'B']).size() # df.groupby(['A', 'B'])['C'].count() New [ ] df.value_counts(subset=['A', 'B']) Note that size and count are not identical, the former counts all rows per group, the latter counts non-null rows only.

4. How to give numbers to each group of a dataframe with...

   stackoverflow.com/questions/36027431

   I want to give numbers to each group in a dataframe. For example, I have the following dataframe: df = data.frame( from = c('a', 'a', 'b'), dest = c('b', 'c', 'd') ) #> df #from dest #1 a b #2 a c #3 b d I want to group by from values and give a group number to each group. This is the expected result:

5. How to return a incremental group number per group in SQL

   stackoverflow.com/questions/14359749

   The query I am using to get these results is : select hl.ts_DateTime, hl.Tagname as [ID], hl.TagValue as [Value], ROW_NUMBER() OVER (PARTITION BY hl.ts_datetime ORDER BY hl.tagname) AS RowFilter. from Table1 hl. So basically, looking at the RowFilter column, I am getting a unique ROW number per ts_DateTime partition.

6. How to number/label data-table by group-number from group_by?

   stackoverflow.com/questions/23026145

   dplyr has a neat function n(), but that gives the number of elements within its group, not the overall number of the group. In data.table this would simply be called .GRP. b) Actually what I really want to assign a string/character label ('A','B',...). But numbering groups by integers is good-enough, because I can then use integer_to_label(i ...

7. Numbering rows within groups in a data frame - Stack Overflow

   stackoverflow.com/questions/12925063

   I would like to add a data.table variant using the rank() function which provides the additional possibility to change the ordering and thus makes it a bit more flexible than the seq_len() solution and is pretty similar to row_number functions in RDBMS.

8. R: add a dplyr group label as a number - Stack Overflow

   stackoverflow.com/questions/50099010

   What I want is a label group_no that indicates the number of categories of the variable name within each id dplyr group. I can not find a solution in the dplyr package itself. I can not find a solution in the dplyr package itself.

9. r - Count number of rows by group using dplyr - Stack Overflow

   stackoverflow.com/questions/22767893

   I am using the mtcars dataset. I want to find the number of records for a particular combination of data. Something very similar to the count(*) group by clause in SQL. ddply() from plyr is working...

10. sql server - row_number () Group by? - Stack Overflow

    stackoverflow.com/questions/12518659

    Here is a solution. You need not worry about the ordering of Cat. Using following SQL you will be able to get unique values for your Date & Cat combination. SELECT. Date, ROW_NUMBER() OVER (PARTITION BY Date, Cat ORDER By Date, Cat) as ROW, Cat, Qty. FROM SOURCE.

11. Combine GROUP BY and ROW_NUMBER () - Stack Overflow

    stackoverflow.com/questions/28372029

    The ROW_NUMBER window function is used to identify the first row for a login_name. The COUNT window function is used to count the number of rows per login_name. The outer query then restricts the results to those login_name that have more than 1 row and only the first row for each login_name is returned.