Get a running total from a list

Question

I\'m reading in items:

for line in sys.stdin:
    line = line.strip()
    data = line.split(\"-\")

If I print data as it is read,

Answer 1

Use a collections.Counter() to count the occurrences:

import collections

lines = [['Adam', '5'],
         ['Peter', '7'],
         ['Adam', '8'],
         ['Lucy', '2'],
         ['Peter', '4']]

counter = collections.Counter()
for data in lines:
    counter[data[0]] += int(data[1])

print(counter)

You'll get:

Counter({'Adam': 13, 'Peter': 11, 'Lucy': 2})

Answer 2

Initialize a defaultdict with type int and use the name as the key

from collections import defaultdict
name_list = defaultdict(int)
for line in sys.stdin:
    line = line.strip()
    data = line.split("-")
    name = data[0]
    value = int(data[1])
    name_list[name] += value
for key, value in name_list.items(): print key, value

Answer 3

I recommend creating a dictonary and updating that as you go. I have assumed your data format for data is a list of lists.

finalList = {}

for name, value in data:
    if name in finalList.keys():
        finalList[name] = finalList[name] + int(value)
    else:
        finalList[name] = int(value)

print(finalList)

Answer 4

Pandas does a very good job in handling this kind of situations

import pandas as pd
df_data=pd.read_csv(filepath_or_buffer=path,sep='_',names =['Name','value'])
df=df_data.groupby(['Name'])['value'].sum()

print df

output

'Adam'     13
'Lucy'      2
'Peter'    11

Input file

Adam_5
Peter_7
Adam_8
Lucy_2
Peter_4