CODEWITHSUNDEEP
python
Rico DutchboyYTB Otto
Rico DutchboyYTB Otto

Reputation: 3

Need help writing and reading with Python

At this moment I wrote this code:

class device:
    naam_device = ''
    stroomverbuirk = 0

aantal_devices = int(input("geef het aantal devices op: "))

i = aantal_devices
x = 0

voorwerp = {}
while i > 0:
    voorwerp[x] = device()
    i = i - 1
    x = x + 1

i = 0

while i < aantal_devices :
    voorwerp[i].naam_device = input("Wat is device %d voor een device: " % (i+1))
    # hier moet nog gekeken worden naar afvang van foute invoer bijv. als gebruiker een string of char invoert ipv een float
    voorwerp[i].stroomverbruik = float(input("hoeveel ampére is uw device?: "))
    i += 1

i = 0
totaal = 0.0

##test while print
while i < aantal_devices:
    print(voorwerp[i].naam_device,voorwerp[i].stroomverbruik)
    #dit totaal moet nog worden geschreven naar een bestand zodat je na 256 invoeren een totaal kan bepalen.
    totaal = totaal + voorwerp[i].stroomverbruik
    i = i + 1

print("totaal ampére = ",totaal)


aantal_koelbox = int(input("Hoeveel koelboxen neemt u mee?: "))

if aantal_koelbox <= 2 or aantal_koelbox > aantal_devices:

    if aantal_koelbox > aantal_devices:
        toestaan = input("Deelt u de overige koelboxen met mede-deelnemers (ja/nee)?: ")
        if toestaan == "ja":
            print("Uw gegevens worden opgeslagen! u bent succesvol geregistreerd.")
        if toestaan == "nee":
            print("Uw gegevens worden niet opgeslagen! u voldoet niet aan de eisen.")
else:
    print("Uw gegevens worden niet opgeslagen! u voldoet niet aan de eisen.")

Now I want to write the value of totaal to a file, and later when I saved 256 of these inputs I want to write another program to read the 256 inputs and give the sum of those and divide that number by 14. If someone could help me on the right track with writing the values and later read them I can try to find out how to do the last part.

But I've been trying for 2 days now and still found no good solution for writing and reading.

Upvotes: 0

Views: 87

Answers (3)

abarnert
abarnert

Reputation: 365657

The tutorial covers this very nicely, as MattDMo points out. But I'll summarize the relevant part here.

The key idea is to open a file, then write each totaal in some format, then make sure the file gets closed at the end.

What format? Well, that depends on your data. Sometimes you have fixed-shape records, which you can store as CSV rows. Sometimes you have arbitrary Python objects, which you can store as pickles. But in this case, you can get away with using the simplest format at all: a line of text. As long as your data are single values that can be unambiguously converted to text and back, and don't have any newline or other special characters in them, this works. So:

with open('thefile.txt', 'w') as f:
    while i < aantal_devices:
        print(voorwerp[i].naam_device,voorwerp[i].stroomverbruik)
        #dit totaal moet nog worden geschreven naar een bestand zodat je na 256 invoeren een totaal kan bepalen.
        totaal = totaal + voorwerp[i].stroomverbruik
        f.write('{}\n'.format(totaal))
        i = i + 1

That's it. The open opens the file, creating it if necessary. The with makes sure it gets closed at the end of the block. The write writes a line consisting of whatever's in totaal, formatted as a string, followed by a newline character.

To read it back later is even simpler:

with open('thefile.txt') as f:
    for line in f:
        totaal = int(line)
        # now do stuff with totaal

Upvotes: 1

Luke Yeager
Luke Yeager

Reputation: 1430

You can write them to a file like so:

with open(os.path.join(output_dir, filename), 'w') as output_file:
    output_file.write("%s" % totaal)

And then sum them like this:

sum = 0
for input_file in os.listdir(output_dir):
    if os.path.isfile(input_file):
        with open(os.path.join(output_dir, input_file), 'r') as infile:
            sum += int(infile.read())
print sum/14

However, I would consider whether you really need to write each totaal to a separate file. There's probably a better way to solve your problem, but I think this should do what you asked for.

P.S. I would try to read your code and make a more educated attempt to help you, but I don't know Dutch!

Upvotes: 0

0xGiddi
0xGiddi

Reputation: 554

Use serialization to store the data in the files and then de-serialize them back in to the original state for computation.

By serializing the data you can restore the data to the original state (value and type, i.e. 1234 as a int and not as string)

Off you go to the docs :) : https://docs.python.org/2/library/pickle.html P.S. For people to be able to help you he code needs to be readable, That way you can get a better answer in the future.

Upvotes: 0

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