CODEWITHSUNDEEP
pythonsorting
Valter Silva
Valter Silva

Reputation: 16656

How to sort a dictionary in Python?

I would like to generate a report where my first column would contain the duration of my SQL queries. That should be sorted by highest duration to the lowest one.

Code:

import os

directory = "./"
results = {}

def isfloat(value):
  try:
    float(value)
    return True
  except ValueError:
    pass

for root,dirs,files in os.walk(directory):
    for file in files:
       if file.endswith(".csv"):
           input_file=open(file, 'r')
           for line in input_file:
                if line:
                    try:
                        duration=line.split(',')[13].split(' ')[1]
                        if isfloat(duration): # check if string is a float
                            results[duration]=line
                    except:
                        pass

output_file = open('report.csv', 'w')
for k,v in sorted(results.items()):
    print k
    output_file.write(k + ',' + v)
output_file.close()

output:

1266.114
1304.450
1360.771
1376.104
1514.518
500.105
519.432
522.594
522.835
528.622
529.664

I wonder why is the sorted() function sorting function is messing my results ?

Upvotes: 1

Views: 70

Answers (2)

Mike Müller
Mike Müller

Reputation: 85612

You can actually convert the strings to floats:

if isfloat(duration): # check if string is a float
    results[float(duration)] = line

or:

try:
    results[float(duration)] = line
except ValueError:
    pass

So you don't need your isfloat() function here.

This should give you properly sorted output.

Upvotes: 1

Martijn Pieters
Martijn Pieters

Reputation: 1125058

Your keys are strings, not numbers. They are sorted lexicographically.

Convert to a number first if you want numeric sorting:

for k,v in sorted(results.items(), key=lambda k_v: float(k_v[0])):

Upvotes: 4

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