VertexFrame tally

---

tally(self, sample_col, count_val)

[BETA] Count number of times a value is seen.

Parameters:

sample_col : unicode

The name of the column from which to compute the cumulative count.

count_val : unicode

The column value to be used for the counts.

Returns:

: _Unit

A cumulative count is computed by sequentially stepping through the rows, observing the column values and keeping track of the number of times the specified count_value has been seen.

Examples

Consider Frame my_frame, which accesses a frame that contains a single column obs:

>>> my_frame.inspect()

  obs:int32
/-----------/
    0
    1
    2
    0
    1
    2

The cumulative count for column obs using count_value = 1 is obtained by:

>>> my_frame.tally('obs', '1')

The Frame my_frame accesses a frame which now contains two columns obs and obsCumulativeCount. Column obs still has the same data and obsCumulativeCount contains the cumulative counts:

>>> my_frame.inspect()

  obs:int32        obs_tally:int32
/----------------------------------/
     0                      0
     1                      1
     2                      1
     0                      1
     1                      2
     2                      2