DKVP I/O examples¶
DKVP I/O in Python¶
Here are the I/O routines:
#!/usr/bin/env python
# ================================================================
# Example of DKVP I/O using Python.
#
# Key point: Use Miller for what it's good at; pass data into/out of tools in
# other languages to do what they're good at.
#
# bash$ python -i dkvp_io.py
#
# # READ
# >>> map = dkvpline2map('x=1,y=2', '=', ',')
# >>> map
# OrderedDict([('x', '1'), ('y', '2')])
#
# # MODIFY
# >>> map['z'] = map['x'] + map['y']
# >>> map
# OrderedDict([('x', '1'), ('y', '2'), ('z', 3)])
#
# # WRITE
# >>> line = map2dkvpline(map, '=', ',')
# >>> line
# 'x=1,y=2,z=3'
#
# ================================================================
import re
import collections
# ----------------------------------------------------------------
# ips and ifs (input pair separator and input field separator) are nominally '=' and ','.
def dkvpline2map(line, ips, ifs):
pairs = re.split(ifs, line)
map = collections.OrderedDict()
for pair in pairs:
key, value = re.split(ips, pair, 1)
# Type inference:
try:
value = int(value)
except:
try:
value = float(value)
except:
pass
map[key] = value
return map
# ----------------------------------------------------------------
# ops and ofs (output pair separator and output field separator) are nominally '=' and ','.
def map2dkvpline(map , ops, ofs):
line = ''
pairs = []
for key in map:
pairs.append(str(key) + ops + str(map[key]))
return str.join(ofs, pairs)
And here is an example using them:
cat polyglot-dkvp-io/example.py
#!/usr/bin/env python
import sys
import re
import copy
import dkvp_io
while True:
# Read the original record:
line = sys.stdin.readline().strip()
if line == '':
break
map = dkvp_io.dkvpline2map(line, '=', ',')
# Drop a field:
map.pop('x')
# Compute some new fields:
map['ab'] = map['a'] + map['b']
map['iy'] = map['i'] + map['y']
# Add new fields which show type of each already-existing field:
omap = copy.copy(map) # since otherwise the for-loop will modify what it loops over
keys = omap.keys()
for key in keys:
# Convert "<type 'int'>" to just "int", etc.:
type_string = str(map[key].__class__)
type_string = re.sub("<type '", "", type_string) # python2
type_string = re.sub("<class '", "", type_string) # python3
type_string = re.sub("'>", "", type_string)
map['t'+key] = type_string
# Write the modified record:
print(dkvp_io.map2dkvpline(map, '=', ','))
Run as-is:
python polyglot-dkvp-io/example.py < data/small
a=pan,b=pan,i=1,y=0.7268028627434533,ab=panpan,iy=1.7268028627434533,ta=str,tb=str,ti=int,ty=float,tab=str,tiy=float
a=eks,b=pan,i=2,y=0.5221511083334797,ab=ekspan,iy=2.5221511083334796,ta=str,tb=str,ti=int,ty=float,tab=str,tiy=float
a=wye,b=wye,i=3,y=0.33831852551664776,ab=wyewye,iy=3.3383185255166477,ta=str,tb=str,ti=int,ty=float,tab=str,tiy=float
a=eks,b=wye,i=4,y=0.13418874328430463,ab=ekswye,iy=4.134188743284304,ta=str,tb=str,ti=int,ty=float,tab=str,tiy=float
a=wye,b=pan,i=5,y=0.8636244699032729,ab=wyepan,iy=5.863624469903273,ta=str,tb=str,ti=int,ty=float,tab=str,tiy=float
Run as-is, then pipe to Miller for pretty-printing:
python polyglot-dkvp-io/example.py < data/small | mlr --opprint cat
a b i y ab iy ta tb ti ty tab tiy
pan pan 1 0.7268028627434533 panpan 1.7268028627434533 str str int float str float
eks pan 2 0.5221511083334797 ekspan 2.5221511083334796 str str int float str float
wye wye 3 0.33831852551664776 wyewye 3.3383185255166477 str str int float str float
eks wye 4 0.13418874328430463 ekswye 4.134188743284304 str str int float str float
wye pan 5 0.8636244699032729 wyepan 5.863624469903273 str str int float str float
DKVP I/O in Ruby¶
Here are the I/O routines:
#!/usr/bin/env ruby
# ================================================================
# Example of DKVP I/O using Ruby.
#
# Key point: Use Miller for what it's good at; pass data into/out of tools in
# other languages to do what they're good at.
#
# bash$ irb -I. -r dkvp_io.rb
#
# # READ
# irb(main):001:0> map = dkvpline2map('x=1,y=2', '=', ',')
# => {"x"=>"1", "y"=>"2"}
#
# # MODIFY
# irb(main):001:0> map['z'] = map['x'] + map['y']
# => 3
#
# # WRITE
# irb(main):002:0> line = map2dkvpline(map, '=', ',')
# => "x=1,y=2,z=3"
#
# ================================================================
# ----------------------------------------------------------------
# ips and ifs (input pair separator and input field separator) are nominally '=' and ','.
def dkvpline2map(line, ips, ifs)
map = {}
line.split(ifs).each do |pair|
(k, v) = pair.split(ips, 2)
# Type inference:
begin
v = Integer(v)
rescue ArgumentError
begin
v = Float(v)
rescue ArgumentError
# Leave as string
end
end
map[k] = v
end
map
end
# ----------------------------------------------------------------
# ops and ofs (output pair separator and output field separator) are nominally '=' and ','.
def map2dkvpline(map, ops, ofs)
map.collect{|k,v| k.to_s + ops + v.to_s}.join(ofs)
end
And here is an example using them:
cat polyglot-dkvp-io/example.rb
#!/usr/bin/env ruby
require 'dkvp_io'
ARGF.each do |line|
# Read the original record:
map = dkvpline2map(line.chomp, '=', ',')
# Drop a field:
map.delete('x')
# Compute some new fields:
map['ab'] = map['a'] + map['b']
map['iy'] = map['i'] + map['y']
# Add new fields which show type of each already-existing field:
keys = map.keys
keys.each do |key|
map['t'+key] = map[key].class
end
# Write the modified record:
puts map2dkvpline(map, '=', ',')
end
Run as-is:
ruby -I./polyglot-dkvp-io polyglot-dkvp-io/example.rb data/small
a=pan,b=pan,i=1,y=0.7268028627434533,ab=panpan,iy=1.7268028627434533,ta=String,tb=String,ti=Integer,ty=Float,tab=String,tiy=Float
a=eks,b=pan,i=2,y=0.5221511083334797,ab=ekspan,iy=2.5221511083334796,ta=String,tb=String,ti=Integer,ty=Float,tab=String,tiy=Float
a=wye,b=wye,i=3,y=0.33831852551664776,ab=wyewye,iy=3.3383185255166477,ta=String,tb=String,ti=Integer,ty=Float,tab=String,tiy=Float
a=eks,b=wye,i=4,y=0.13418874328430463,ab=ekswye,iy=4.134188743284304,ta=String,tb=String,ti=Integer,ty=Float,tab=String,tiy=Float
a=wye,b=pan,i=5,y=0.8636244699032729,ab=wyepan,iy=5.863624469903273,ta=String,tb=String,ti=Integer,ty=Float,tab=String,tiy=Float
Run as-is, then pipe to Miller for pretty-printing:
ruby -I./polyglot-dkvp-io polyglot-dkvp-io/example.rb data/small | mlr --opprint cat
a b i y ab iy ta tb ti ty tab tiy
pan pan 1 0.7268028627434533 panpan 1.7268028627434533 String String Integer Float String Float
eks pan 2 0.5221511083334797 ekspan 2.5221511083334796 String String Integer Float String Float
wye wye 3 0.33831852551664776 wyewye 3.3383185255166477 String String Integer Float String Float
eks wye 4 0.13418874328430463 ekswye 4.134188743284304 String String Integer Float String Float
wye pan 5 0.8636244699032729 wyepan 5.863624469903273 String String Integer Float String Float