how to count items/boolean after if-statements (python)

Question

I have a csv where I need to count the total number for each category:

New_Cell[2]                            Category I need to count

1                                            [A01]
1                                            [A01]
0                                            [A01]
1                                            [A01]
0                                            [A02]
1                                            [A02]
1                                            [A02]
2                                            [A02]
1                                            [A02]

I need it to count each occurrence of TRUE for the if-condition so that it will look like:

[A01] : 3

instead of:

 1 1 1

I currently have:

A01 = "[A01] Officials"

data_out = open("mentees_all_attributes.csv", "rU")
reader = csv.reader(data_out)
next(reader,None)
for line in reader:
    cells = line
    new_cell = cells[0], cells[6], cells[7], cells[8], cells[9], cells[10] # name, # of participation, primary occupation/industry, secondary occupation/industry
    if int(new_cell[1]) > 0: #Isolate all the participants with more than 0
        primary = new_cell[2]
        if primary == A01:
            if True:
                counts =+ 1
                print counts
data_out.close()

I think you mean counts += 1. And the if True can be omitted, of course. — Stephan W.
– Stephan W., Commented Jun 29, 2016 at 13:55
counts =+ 1 means counts = (+1) which means counts = 1. Try counts += 1. — Łukasz Rogalski
– Łukasz Rogalski, Commented Jun 29, 2016 at 13:56

Kevin · Accepted Answer · 2016-06-29 13:56:18Z

1

Initialize counts before the loop begins, increment it when your condition succeeds, and only print it after the loop ends.

counts = 0
for line in reader:
    cells = line
    new_cell = cells[0], cells[6], cells[7], cells[8], cells[9], cells[10] # name, # of participation, primary occupation/industry, secondary occupation/industry
    if int(new_cell[1]) > 0: #Isolate all the participants with more than 0
        primary = new_cell[2]
        if primary == A01:
            counts += 1
print counts

Note that counts =+ 1 and counts += 1 do very different things. The first means "assign positive one to counts" and the second one means "increment count's value by one"

answered Jun 29, 2016 at 13:56

Kevin

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4 Comments

peaceandiago Over a year ago

It outputs 1 2 3 instead, can I sum it up so it can just output 3 or able to print as A01: 3 ?

Kevin Over a year ago

Did you put the print outside the loop? If you have exactly one print statement and it's at the global scope not inside any loops, then exactly one object should be printed.

peaceandiago Over a year ago

Thank you that's it. I just have one more question, if I have to count multiple categories, do I have to have multiple count global variables?

Kevin Over a year ago

In that case I'd recommend using a single collections.Counter, which is designed exactly for the purpose of counting multiple things.

Eric La Fevers · Accepted Answer · 2016-06-29 14:42:14Z

0

To add on to Kevin's answer, you can also use a dictionary to increment the counts for multiple categories.

categories = {}
counts = 0
for line in reader:
    cells = line
    new_cell = cells[0], cells[6], cells[7], cells[8], cells[9], cells[10]
    if int(new_cell[1]): 
        primary = new_cell[2]
        if primary:
            if primary not in categories.keys():
                categories[primary] = 0
            categories[primary] += 1

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

answered Jun 29, 2016 at 14:42

Eric La Fevers

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