How do I format variables in Python

Question

I'm currently having a problem in python, what I am trying to do is go through 6 arrays checking if there is a negative number or not and then adding one to the corresponding variable.

I've tried various things to fix this however there is no real documentation that I can find online that will help me

BusA = ["-1","1","-1","1"]
BusB = ["-1","1","-1","1"]
BusC = ["-1","1","-1","1"]
BusD = ["-1","1","-1","1"]
BusE = ["-1","1","-1","1"]
BusF = ["-1","1","-1","1"]

Buses = "ABCDEF"

BusALate, BusBLate, BusCLate, BusDLate, BusELate, BusFLate = 0, 0, 0, 0, 0, 0

for c in Buses:
  Array = eval("Bus" + str(c))
  for i in Array:
    if(int(i) < 0):
      eval("Bus"+c+"Late") += 1

print(BusALate, BusBLate, BusCLate, BusDLate, BusELate, BusFLate)

If possible I just need a way to format the variable in the if so that it can progressively go through changing it to BusALate, BusBLate etc... and adding when it has found the negative number.

You should really use a dict: busses = {"A": [-1, 1, -1, 1], B: [....], ...} and integers, if your values are meant to be numbers. So, you would also have busses_late = {A: 0, ...} — Thierry Lathuille
– Thierry Lathuille, Commented Feb 15, 2019 at 9:25

Aaron · Accepted Answer · 2019-02-15 09:47:03Z

1

Building upon Thierry Lathuille's suggestion, here is how using dictionnaries can simplify your code :

bus_schedules= {
    "A" : ["-1","1","-1","1"],
    "B" : ["-1","1","-1","1"],
    "C" : ["-1","1","-1","1"],
    "D" : ["-1","1","-1","1"],
    "E" : ["-1","1","-1","1"],
    "F" : ["-1","1","-1","1"]
}

bus_late = {"A" : 0, "B" : 0, "C" : 0, "D" : 0, "E" : 0, "F" : 0}

for (bus_name, bus_times) in bus_schedules.items():
    for i in bus_times :
        if (int(i) < 0):
            bus_late[bus_name]+=1

print(bus_late)

answered Feb 15, 2019 at 9:47

Aaron

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Rémi Baudoux · Accepted Answer · 2019-02-15 09:33:26Z

0

import numpy as np

buses =  np.array([[-1,1,-1,1],
                   [-1,1,-1,1],
                   [-1,1,-1,1],
                   [-1,1,-1,1],
                   [-1,1,-1,1],
                   [-1,1,-1,1]])

print(np.sum(buses<0, axis=1))

answered Feb 15, 2019 at 9:33

Rémi Baudoux

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Jan · Accepted Answer · 2019-02-15 09:47:58Z

0

String conversion and dict comprehension in one step:

busses = {'A':["-1","1","-1","1"],
          'B': ["-1","1","-1","1"],
          'C': ["-1","1","-1","1"],
          'D': ["-1","1","-1","1"],
          'E': ["-1","1","-1","1"],
          'F': ["-1","1","-1","1"]}

busses = {key: [(value + 1) if value < 0 else value
                for x in lst
                for value in [int(x)]]
          for key, lst in busses.items()}
print(busses)

This yields

{'A': [0, 1, 0, 1], 
 'B': [0, 1, 0, 1], 
 'C': [0, 1, 0, 1], 
 'D': [0, 1, 0, 1], 
 'E': [0, 1, 0, 1], 
 'F': [0, 1, 0, 1]}

answered Feb 15, 2019 at 9:47

Jan

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