在python tkinter中从CSV文件输出单个单元格

Question

This is meant to display a single element name from a CSV periodic table (atomic symbol in row 0, name in row 1) in a new label in a tkinter label. The user should be able to entry an atomic symbol, click the find button and the name be output. However so far, it does not print anything, and I am unsure which part is going wrong as I am fairly new to tkinter.

The current code:

import tkinter as tk
base_container = tk.Tk()
element = tk.StringVar()

def search(element):
    import csv
    choice = element 
    with open('Periodic_Table.csv') as file:
        csv_file = csv.reader(open('Periodic_Table.csv', "rt"), delimiter=",")
        for row in csv_file:
            if choice == str(row[0]):
                tk.Label(base_container, text=str(row[1])).grid(row=4, column=0)

entry = tk.Label(base_container, text="Enter a chemical symbol:").grid(row=0, column=0, sticky="NE")
text = tk.Entry(base_container, width= 30, textvariable=element).grid(row=0, column=1, padx=2, pady=2, sticky="NE", columnspan=4)

Find = tk.Button(base_container, text="Find", command=lambda: search('element'))
Find.grid(row=30, column=10, sticky="SW", padx=2, pady=2)

Quit = tk.Button(base_container, text="Quit").grid(row=50, column=10, sticky="SW", padx=2, pady=2)
base_container.mainloop()

Periodic_Table.csv starts as follows:

H, Hydrogen
He, Helium
Li, Lithium
Be, Beryllium
B, Boron
C, Carbon

Answer 1

There are a few problems with your code. As Martin mentioned, you're opening the CSV file twice. And there's no need to open it & read every time you want to perform a search. It's much more efficient to read it once into some kind of collection, and then perform your search on that collection.

We could save the periodic table data into a list, but it's much better to use a dictionary. That way we can instantly get the element name by using the symbol as the key.

Another problem that I hinted at earlier is that you're passing the string 'element' to your search function instead of a string containing the element's symbol. And since the periodic table doesn't contain the word 'element' the search would always fail.

We don't actually need to pass anything to search : we can get it to retrieve the current contents of the Entry via the element StringVar.

Also, as I mentioned above, it's not a good idea to make a new Label each time you want to update the output. The old Labels will still exist, but they'll be buried under the newer ones. Instead, create a single Label and update its text via its .config method.

Here's a repaired version of your program.

import csv
import tkinter as tk

# Read the periodic_table data and save it to a dictionary, keyed by the symbol
periodic_table = {}
with open('Periodic_Table.csv', newline='') as f:
    reader = csv.reader(f, delimiter=",", skipinitialspace=True)
    for sym, name in reader:
        periodic_table[sym] = name

base_container = tk.Tk()
element = tk.StringVar()

def search():
    sym = element.get() 
    name = periodic_table.get(sym, 'Not found')
    element_label.config(text=name) 

tk.Label(base_container, text="Enter a chemical symbol:").grid(row=0, column=0, sticky="NE")
tk.Entry(base_container, width=30, textvariable=element).grid(row=0, column=1, padx=2, pady=2, sticky="NE", columnspan=4)

element_label = tk.Label(base_container, text='')
element_label.grid(row=4, column=0)

tk.Button(base_container, text="Find", command=search).grid(row=30, column=10, sticky="SW", padx=2, pady=2)
tk.Button(base_container, text="Quit", command=base_container.destroy).grid(row=50, column=10, sticky="SW", padx=2, pady=2)

base_container.mainloop()