adam Wadsworth
Reputation: 784
pull out column 2,3 of a 2d array in python
hi all i have a 2d array and i want to create a new 2d array with only the column 2,3
here is my code
#!/user
# -*- coding: utf-8 -*-
import csv
import urllib2
import numpy as np
url = 'https://api.bmreports.com/BMRS/FUELINST/v1?APIKey=66ky5jo5p5w0vbd&ServiceType=CSV'
url2 = 'https://api.bmreports.com/BMRS/FUELINSTHHCUR/v1?APIKey=66ky5jo5p5w0vbd&ServiceType=CSV'
response = urllib2.urlopen(url2)
cr = csv.reader(response)
arr = np.genfromtxt(response,delimiter=",", skip_header=1, skip_footer=2,dtype=None)
data = arr[:, [1:2]]
print data
so the data comes back like this
[('FUELINSTHHCUR', 'CCGT', 10430, 35.8, 10282, 35.2, 205996, 32. )
('FUELINSTHHCUR', 'OCGT', 0, 0. , 0, 0. , 17, 0. )
('FUELINSTHHCUR', 'OIL', 0, 0. , 0, 0. , 0, 0. )
('FUELINSTHHCUR', 'COAL', 0, 0. , 0, 0. , 0, 0. )
('FUELINSTHHCUR', 'NUCLEAR', 6963, 23.9, 6970, 23.9, 167591, 26. )
('FUELINSTHHCUR', 'WIND', 6986, 24. , 7061, 24.2, 160036, 24.9)
('FUELINSTHHCUR', 'PS', 297, 1. , 412, 1.4, 8136, 1.3)
('FUELINSTHHCUR', 'NPSHYD', 322, 1.1, 319, 1.1, 8015, 1.2)
('FUELINSTHHCUR', 'OTHER', 129, 0.4, 128, 0.4, 3093, 0.5)
('FUELINSTHHCUR', 'INTFR', 1494, 5.1, 1494, 5.1, 31731, 4.9)
('FUELINSTHHCUR', 'INTIRL', 0, 0. , 0, 0. , 2650, 0.4)
('FUELINSTHHCUR', 'INTNED', 882, 3. , 880, 3. , 18991, 2.9)
('FUELINSTHHCUR', 'INTEW', 0, 0. , 0, 0. , 0, 0. )
('FUELINSTHHCUR', 'BIOMASS', 1608, 5.5, 1630, 5.6, 37688, 5.9)]
i'm trying to create a new 2d array that only brings back columns back so it looks like this
[('CCGT', 10430)
('OCGT', 0)
('OIL', 0)
('COAL', 0)
('NUCLEAR', 6963)
('WIND', 6986)
('PS', 297)
('NPSHYD', 322)
('OTHER', 129)
('INTFR', 1494)
('INTIRL', 0)
('INTNED', 882)
('INTEW', 0)
('BIOMASS', 1608)]
Upvotes: 0
Views: 278
Answers (2)
webmite
Reputation: 575
If you review this code sample it may help you.
It assumes that the first values you have collected turn out to be individual strings in a numpy array....so each line contains commas, and quoted elements but they are all embedded in a single element.
The var 'lst' is a list used to step through all the array elements and create multidimensional list of lists containing the comma separated elements as individual strings.
The var 'tmp' is a numpy array constructed of the newly parsed 'lst'.
The var 'data' is the sliced numpy array from 'tmp' with just the columns you were looking for.
Hope that helps...
import numpy as np
def ElementSplit(x) : return x.split(",")
ElementSplit = np.vectorize(ElementSplit)
arr = np.array([["'FUELINSTHHCUR', 'CCGT', 10430, 35.8, 10282, 35.2, 205996, 32. "],
["'FUELINSTHHCUR', 'OCGT', 0, 0. , 0, 0. , 17, 0. "],
[" 'FUELINSTHHCUR', 'OIL', 0, 0. , 0, 0. , 0, 0. "],
[" 'FUELINSTHHCUR', 'COAL', 0, 0. , 0, 0. , 0, 0. "],
[" 'FUELINSTHHCUR', 'NUCLEAR', 6963, 23.9, 6970, 23.9, 167591, 26. "],
[" 'FUELINSTHHCUR', 'WIND', 6986, 24. , 7061, 24.2, 160036, 24.9"],
[" 'FUELINSTHHCUR', 'PS', 297, 1. , 412, 1.4, 8136, 1.3"],
[" 'FUELINSTHHCUR', 'NPSHYD', 322, 1.1, 319, 1.1, 8015, 1.2"],
[" 'FUELINSTHHCUR', 'OTHER', 129, 0.4, 128, 0.4, 3093, 0.5"],
[" 'FUELINSTHHCUR', 'INTFR', 1494, 5.1, 1494, 5.1, 31731, 4.9"],
[" 'FUELINSTHHCUR', 'INTIRL', 0, 0. , 0, 0. , 2650, 0.4"],
[" 'FUELINSTHHCUR', 'INTNED', 882, 3. , 880, 3. , 18991, 2.9"],
[" 'FUELINSTHHCUR', 'INTEW', 0, 0. , 0, 0. , 0, 0. "],
[" 'FUELINSTHHCUR', 'BIOMASS', 1608, 5.5, 1630, 5.6, 37688, 5.9"]])
print " --arr--"
print arr
lst = []
for items in arr:
lst.append(items[0].split(", "))
print " --lst--"
print lst
exit
#data = arr[:]
tmp = np.array(lst)
print " --tmp--"
print tmp
data = tmp[:,[1,2]]
print " --data--"
print data
and the output looks like this....
$python main.py
--arr--
[["'FUELINSTHHCUR', 'CCGT', 10430, 35.8, 10282, 35.2, 205996, 32. "]
["'FUELINSTHHCUR', 'OCGT', 0, 0. , 0, 0. , 17, 0. "]
[" 'FUELINSTHHCUR', 'OIL', 0, 0. , 0, 0. , 0, 0. "]
[" 'FUELINSTHHCUR', 'COAL', 0, 0. , 0, 0. , 0, 0. "]
[" 'FUELINSTHHCUR', 'NUCLEAR', 6963, 23.9, 6970, 23.9, 167591, 26. "]
[" 'FUELINSTHHCUR', 'WIND', 6986, 24. , 7061, 24.2, 160036, 24.9"]
[" 'FUELINSTHHCUR', 'PS', 297, 1. , 412, 1.4, 8136, 1.3"]
[" 'FUELINSTHHCUR', 'NPSHYD', 322, 1.1, 319, 1.1, 8015, 1.2"]
[" 'FUELINSTHHCUR', 'OTHER', 129, 0.4, 128, 0.4, 3093, 0.5"]
[" 'FUELINSTHHCUR', 'INTFR', 1494, 5.1, 1494, 5.1, 31731, 4.9"]
[" 'FUELINSTHHCUR', 'INTIRL', 0, 0. , 0, 0. , 2650, 0.4"]
[" 'FUELINSTHHCUR', 'INTNED', 882, 3. , 880, 3. , 18991, 2.9"]
[" 'FUELINSTHHCUR', 'INTEW', 0, 0. , 0, 0. , 0, 0. "]
[" 'FUELINSTHHCUR', 'BIOMASS', 1608, 5.5, 1630, 5.6, 37688, 5.9"]]
--lst--
[["'FUELINSTHHCUR'", "'CCGT'", '10430', '35.8', '10282', '35.2', '205996', '32. '], ["'FUELINSTHHCUR'", "'OCGT'", ' 0', ' 0. ', ' 0', ' 0. ', ' 17', ' 0. '], [" 'FUELINSTHHCUR'", "'OIL'", ' 0', ' 0. ', ' 0', ' 0. ', ' 0', ' 0. '], [" 'FUELINSTHHCUR'", "'COAL'", ' 0', ' 0. ', ' 0', ' 0. ', ' 0', ' 0. '], [" 'FUELINSTHHCUR'", "'NUCLEAR'", ' 6963', '23.9', ' 6970', '23.9', '167591', '26. '], [" 'FUELINSTHHCUR'", "'WIND'", ' 6986', '24. ', ' 7061', '24.2', '160036', '24.9'], [" 'FUELINSTHHCUR'", "'PS'", ' 297', ' 1. ', ' 412', ' 1.4', ' 8136', ' 1.3'], [" 'FUELINSTHHCUR'", "'NPSHYD'", ' 322', ' 1.1', ' 319', ' 1.1', ' 8015', ' 1.2'], [" 'FUELINSTHHCUR'", "'OTHER'", ' 129', ' 0.4', ' 128', ' 0.4', ' 3093', ' 0.5'], [" 'FUELINSTHHCUR'", "'INTFR'", ' 1494', ' 5.1', ' 1494', ' 5.1', ' 31731', ' 4.9'], [" 'FUELINSTHHCUR'", "'INTIRL'", ' 0', ' 0. ', ' 0', ' 0. ', ' 2650', ' 0.4'], [" 'FUELINSTHHCUR'", "'INTNED'", ' 882', ' 3. ', ' 880', ' 3. ', ' 18991', ' 2.9'], [" 'FUELINSTHHCUR'", "'INTEW'", ' 0', ' 0. ', ' 0', ' 0. ', ' 0', ' 0. '], [" 'FUELINSTHHCUR'", "'BIOMASS'", ' 1608', ' 5.5', ' 1630', ' 5.6', ' 37688', ' 5.9']]
--tmp--
[["'FUELINSTHHCUR'" "'CCGT'" '10430' '35.8' '10282' '35.2' '205996' '32. ']
["'FUELINSTHHCUR'" "'OCGT'" ' 0' ' 0. ' ' 0' ' 0. ' ' 17' ' 0. ']
[" 'FUELINSTHHCUR'" "'OIL'" ' 0' ' 0. ' ' 0' ' 0. ' ' 0' ' 0. ']
[" 'FUELINSTHHCUR'" "'COAL'" ' 0' ' 0. ' ' 0' ' 0. ' ' 0' ' 0. ']
[" 'FUELINSTHHCUR'" "'NUCLEAR'" ' 6963' '23.9' ' 6970' '23.9' '167591'
'26. ']
[" 'FUELINSTHHCUR'" "'WIND'" ' 6986' '24. ' ' 7061' '24.2' '160036' '24.9']
[" 'FUELINSTHHCUR'" "'PS'" ' 297' ' 1. ' ' 412' ' 1.4' ' 8136' ' 1.3']
[" 'FUELINSTHHCUR'" "'NPSHYD'" ' 322' ' 1.1' ' 319' ' 1.1' ' 8015'
' 1.2']
[" 'FUELINSTHHCUR'" "'OTHER'" ' 129' ' 0.4' ' 128' ' 0.4' ' 3093'
' 0.5']
[" 'FUELINSTHHCUR'" "'INTFR'" ' 1494' ' 5.1' ' 1494' ' 5.1' ' 31731'
' 4.9']
[" 'FUELINSTHHCUR'" "'INTIRL'" ' 0' ' 0. ' ' 0' ' 0. ' ' 2650'
' 0.4']
[" 'FUELINSTHHCUR'" "'INTNED'" ' 882' ' 3. ' ' 880' ' 3. ' ' 18991'
' 2.9']
[" 'FUELINSTHHCUR'" "'INTEW'" ' 0' ' 0. ' ' 0' ' 0. ' ' 0'
' 0. ']
[" 'FUELINSTHHCUR'" "'BIOMASS'" ' 1608' ' 5.5' ' 1630' ' 5.6' ' 37688'
' 5.9']]
--data--
[["'CCGT'" '10430']
["'OCGT'" ' 0']
["'OIL'" ' 0']
["'COAL'" ' 0']
["'NUCLEAR'" ' 6963']
["'WIND'" ' 6986']
["'PS'" ' 297']
["'NPSHYD'" ' 322']
["'OTHER'" ' 129']
["'INTFR'" ' 1494']
["'INTIRL'" ' 0']
["'INTNED'" ' 882']
["'INTEW'" ' 0']
["'BIOMASS'" ' 1608']]
Upvotes: 0
Kasravnd
Reputation: 107347
Firstly you need to use a Numpy array for preserving your items not a list, then you can pass the column indices in a list to the second axis to get the desire results:
data = arr[:, [2, 3]]
Or slice like following:
data = arr[:, 2:4]
Also if the string you're reading is correctly formatted instead of using csv
you can use fromstring()
function to load your data.
Upvotes: 1
Related Questions
- How to get values from a 2-d Array with indices
- How do you extract a column from a multi-dimensional array?
- How do I extract elements from a 2D array using a 2D array of indices?
- Extract and then map a column in a 2D numpy array
- how to return all but one column of a 2d array?
- Extract certain columns of 3d numpy array
- How can get a part of a 2D array?
- How to select specific rows and columns in 2d array
- How to extract array from the first element of triples in 2d array of triples using numpy
- How can I get a column from a 2D python array?