This crate / package is a rust module that handles streaming input and output. It's purpose is to tally or accumulate  values for  a streaming set of keys. It is designed to be stupidly simple and consume / produce whitespace seperate values.

# Key Value Counts

I use this library to parse simple journal-like logs where each line is of the form:

```
2021-03-01 warnings:3 error ... (other items with optional counts)
```

Supposing I wanted to do some processing on this data. This is a very readable / writeable format, but is not standard.

We can use 
`kvc-stream` to covert it into something more lika a [stream of k-value pairs](https://www.edureka.co/blog/kafka-streams/#stream) 
or 
`kvc-df` to convert it to a [pandas dataframe](https://pandas.pydata.org/pandas-docs/stable/getting_started/intro_tutorials/01_table_oriented.html#min-tut-01-tableoriented)

# Spec

The kvc journal format is very simple.

- Each line is a "frame"
- A frame has an optional "date header"
- A frame is composed of a string of whitespace-seperated keys with optional counts per key
- A '#' ends the frame, and is useful for comments

These are valid frames, one per line:

```
a
event event
2021-04-01 april_fools_pranks:4
2021-03-01 key another_key a-third-key <weird-symbols_ar_ok!> this_has_occured_three_times:3 this_twice this_twice
2021-04-02 # Nothing happened that day
```

Suppose that's stored in `data.txt`. (try it!)

Running `<data.txt kvc-stream` produces:

```
1 a 1
2 event 2
3 Date 2021-04-01
3 april_fools_pranks 4
4 Date 2021-03-01
4 <weird-symbols_ar_ok!> 1
4 a-third-key 1
4 this_has_occured_three_times 3
4 this_twice 2
4 key 1
4 another_key 1
5 Date 2021-04-02
```

Running `cat data.txt | kvc-df` (or ` < data.txt kvc-df ` ) produces: 

```
index  april_fools_pranks  this_twice  a  <weird-symbols_ar_ok!>  event  Date        a-third-key  key  this_has_occured_three_times  another_key
1      0                   0           1  0                       0      0           0            0    0                             0
2      0                   0           0  0                       2      0           0            0    0                             0
3      4                   0           0  0                       0      2021-04-01  0            0    0                             0
4      0                   2           0  1                       0      2021-03-01  1            1    3                             1
5      0                   0           0  0                       0      2021-04-02  0            0    0                             0
```

OK, so I actually aligned the text and output an index with ` cat data.txt | kvc-df -i | column -t `

I use this to keep a journal of events and easily scrape it for analysis in other programs or databases.