CODEWITHSUNDEEP
pythonpython-3.x
saltcracker
saltcracker

Reputation: 321

Print out indexes of same values in file/list

I have a textfile with data. For example, I want to print out all the values for "animal". So when "animal" is choosen, it will print out "Monkey", "Elephant" and "Dog". It works somewhat, but it only prints out the first value. For example if I choose "animal", it only print out Monkey.

Is there a way to make it print out all of them? Maybe there is better ways to do it?

Data2.txt:

Adidas, shoe
Monkey, animal
Soup, food
Elephant, animal
Dog, animal 
Taco, food

file = open('data2.txt')
data = file.readlines

stuffs = []
types = []


for line in data():
 line = line.strip()
 stuff, type = line.split(', ')
 stuffs.append(stuff)
 types.append(type)

animals = types.index('animal')
print (stuffs[animals])

Upvotes: 2

Views: 104

Answers (6)

Padraic Cunningham
Padraic Cunningham

Reputation: 180481

Use a collections.defaultdict to group the types and the csv module to parse your file:

import csv
from collections import defaultdict
with open("test.txt") as f:
    # create rows splitting on commas 
    r = csv.reader(f, skipinitialspace=True)
    # create dict to store all the types
    d = defaultdict(list)
    # v = row[0], k = row[1]
    for v,k in r:
        d[k].append(v)

Output:

defaultdict(<class 'list'>, {'shoe': ['Adidas'], 
                           'food': ['Soup', 'Taco'], 
                           'animal': ['Monkey', 'Elephant', 'Dog']})

Then just lookup by key:

print(d["animal"])
print(d["shoe"])

['Monkey', 'Elephant']
['Adidas']

You don't ever need to call readlines unless you actually want a list, you could have iterated over the file object or simply passed it to the csv module and iterate over the reader object as in the code above.

Upvotes: 1

LetzerWille
LetzerWille

Reputation: 5668

d = {}
with open('data','r' ) as f:
    for line in f:
       le, r = line.split(',')
       d.setdefault(r.strip(),[]).append(le.strip())

for k,v in d.items():
    print(k,v)

shoe ['Adidas']
food ['Soup', 'Taco']
animal ['Monkey', 'Elephant', 'Dog']

Upvotes: 1

farhawa
farhawa

Reputation: 10417

Use numpy this way:

import numpy as np

a = np.loadtxt("myFile")

#Then it's simple!

a[a[:,1] == 'animal'][0]

Upvotes: 0

tobias_k
tobias_k

Reputation: 82929

The way you populate your lists, you have one list with animals, and one with the corresponding types, in the same position. Using index, you will only get the first match, but you need all.

One way would be to use zip to iterate pairs of animals and types, and print each animal where the type is correct.

for s, t in zip(stuffs, types):
    if t == "animal":
         print(s)

Or you can use a list comprehension to collect all the animals in a list:

>>> [s for s, t in zip(stuffs, types) if t == "animal"]
['Monkey', 'Elephant', 'Dog']

Or, change the way you store your data. For example, instead of having two lists with corresponding indices and zipping those lists back to one list of pairs, you could create a list of pairs to start with:

pairs = []
for line in data():
    line = line.strip()
    pairs.append(line.split(', '))

print([s for s, t in pairs if t == "animal"])

Or even use a dictionary, mapping types to stuffs, as suggested in some of the other answers.

Upvotes: 1

jh314
jh314

Reputation: 27802

I think a better idea would be to use a dict:

file = open('data2.txt')
data = file.readlines

categories = {}

for line in data():
 line = line.strip()
 stuff, type = line.split(', ')
 categories.setdefault(type, []).append(stuff)

print (categories['animal'])

Upvotes: 1

ergonaut
ergonaut

Reputation: 7057

You need to loop through types because types.index('animal') will only return you the first one. Once you find the index, you can find the corresponding index in stuffs. Try this:

i = 0
for type in types:
  if (type == 'animal'):
    print (stuffs[i])
  i = i + 1

Upvotes: 1

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