TypeError: list indices must be integers or slices, not str

I'm having the error below with a project and looked for some explanation (like this page) and I get the cause of the error. But I couldn't figure out what might be the problem in this case.

Traceback (most recent call last):
  File "c:\Users\luisa.oliveira\Programs\VScode\dashboard-ecg-atualizado\app\views\dashboard.py", line 688, in n_protocolo_callback
    g1, quantidades = graficos(
  File "c:\Users\luisa.oliveira\Programs\VScode\dashboard-ecg-atualizado\app\views\dashboard.py", line 51, in graficos
    desejados = ids[ids["ID"] == numero]["Protocolo"]
TypeError: list indices must be integers or slices, not str

some background to line 688:

def n_protocolo_callback(data, laudos, idade, sexo, operacao, pagina, quais_graficos):

    idade = faixas_idades.get(idade)
    idade_inicial, idade_final = None, None
    sexo = sexos.get(sexo)
    if idade:
        idade_inicial, idade_final = idade
    ids = laudos

    dados.loc[:, "Data"] = pd.to_datetime(dados.loc[:, "Data"])
    # cria primeiro gráfico
    g1, quantidades = graficos(
        dados, ids, data, laudos, [idade_inicial, idade_final], sexo
    )

beginnig of func: graficos()

def graficos(dados, ids, data, laudos, idade, sexo):
    data_inicial, data_final = data
    idade_inicial, idade_final = idade
    figura = []
    n_laudos = [numeros_diagnosticos.get(laudo) for laudo in laudos]
    mostrar = []

    for i, (nome, numero) in enumerate(zip(laudos, n_laudos)):
        desejados = ids[ids["ID"] == numero]["Protocolo"]

Edit: "ids" is a csv with 2 columns (ID and Protocolo) that's read by pd.read_csv. "numero" is an integer and "nome" a string

I think the problem has to do with indexing ids with "ID", but I'm not sure if that's right or how to solve it

CodePudding user response：

Global variables can be accessed inside of functions as long as they are on the right side of an assignment:

# Global variable
x = 3

def fun():
   # assign value of global variable x to local variable y
   y = x

If, however you have a variable with the same name of a global variable on the left side of an assignment, you'll create a local variable inside your function:

# Global variable
x = 3

def fun():
   # Initialize local variable
   x = 5
   print(x)

print(x)  # prints 3
fun()     # prints 5
print(x)  # prints 3

fun() assigns a different value to x but it doesn't affect the global variable outside.

If you define a function, all parameters are of local scope. When you pass those arguments to a function, Python checks in the current scope for all variable names and only goes to the next scope if it doesn't find all variables.

# Global variabl
x = 3

def outer():
   def inner(x):
      print(x)
   inner(x)

outer()  # Prints 3

Try to avoid using global variables as they obfuscate your code. I removed the parts not affecting your outcome for this explanation:

import pandas as pd

# global variables
ids = pd.DataFrame({"ID":[1, 2, 3, 4, 5, 6], "Protocolo":[444, 555, 666, 777, 888, 999,]})

# Presumably some list as this caused your TypeError
laudos = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]


def n_protocolo_callback(laudos):
    # Initialize a local variable ids with values from laudos
    ids = laudos
    # Calling graficos with local variable of ids
    g1, quantidades = graficos(ids, laudos)


# Define local variable of ids in the scope of function graficos
def graficos(ids, laudos):
    n_laudos = [numeros_diagnosticos.get(laudo) for laudo in laudos]

    for i, (nome, numero) in enumerate(zip(laudos, n_laudos)):
        # Accessing local variable ids
        desejados = ids[ids["ID"] == numero]["Protocolo"]

# Calling n_protocolo_callback will cause a TypeError
# n_protocolo_callback(laudos)

The error is caused as you re-assigned ids with the values of laudos inside n_protocolo_callback and then passed the local variable to graficos.

When you use global variables you don't need to add them as parameter to your function.

The TypeError is caused as a list can't be indexed with a string. As the error message reads you can index either using integer or slices, i.e:

l = [555, 666, 777, 888, 999]

# Accessing first element using integer
print(l[0])  # prints 555

# Accessing first 3 elements using slice:
print(l[0:3])  # prints [555, 666, 777]