Do “if x in dic” Statements Look at Keys or Values in Python Dictionaries?

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Problem scenario
In Python if you test if a value is in a dictionary, does it look at the keys, the values, or both?

For example, you have code like this:

good_kv = {}
good_kv[”a”] = 1
good_kv[”b”] = 2
good_kv[”c”] = 3

if “b” in good_kv:
print(“The value is in the dictionary!”)
else:
print(“The value is not in the dictionary!”)

print (“testing keys of dictionary above and values of dictionaries below”)

if 3 in good_kv:
print(“The value is in the dictionary!”)
else:
print(“The value is not in the dictionary!”)

Do dictionaries keys,

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In Python when Source Code is Used to Create Byte Code, what is the Intermediate Content?

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Problem scenario
Python can compile source code. There is a process that happens. What form does the code take in the interim (before byte code is created)?

Solution
Abstract Syntax Tree (according to page 175 of Expert Python Programming by Jaworski and Ziade). There is an ast module that allows you to interact with the Abstract Syntax Tree via its grammar.

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Why Cannot You Browse to a URL Path with a File Name in a Web Browser when the index.html File is Available?

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Problem scenario
You know foobar.html is in a directory on a web server that houses index.html. You cannot go to foobar.html in a web browser — but you can go to index.html. How do you fix this?

Possible solution #1
Are the permissions of foobar.html different from index.html? Is there a slight spelling error in the file name on the back-end?

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Using Python How Do You Print Log Entries for a Given Time Range?

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Problem scenario
Using Python, you want to parse a log file. You want to print out entries that have a datetime stamp that are within 24 hours of a given date.

The log file is in this format:

Sep 18 07:28:11 server1 sshd[29284]: Received disconnect from 115.52.17.109 port 46970:11: Bye Bye [preauth]
Sep 18 07:28:11 server1 sshd[29284]: Disconnected from 115.52.17.109 port 46970 [preauth]
Sep 18 07:28:11 server1 sshd[29282]: Failed password for root from 51.10.7.109 port 24844 ssh2
Sep 18 07:28:13 server1 sshd[29287]: pam_unix(sshd:auth): authentication failure; …

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How Do You Set a Date-Time Value with a Default Year in Python?

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Problem scenario
You are printing out some dates with a Python program. You are using the datetime module and the strptime method. The year is always defaulting to 1900 because the log entries have no year designated in them. How do you seed the dates with a specific year of your choice?

Solution
Here is an example of how to seed the dates with the year 2021 (but it assumes you have a file name auth.log with dates without years in it):

import datetime
from datetime import datetime, …

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How Do You Troubleshoot the Python Problem “ValueError: time data … does not match %m”?

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Problem scenario
You are trying to parse a log file with Python. The date entries use abbreviated spellings of months — not integer month values. You get an error like this:

“ValueError: time data ‘Jul 15 06:10:32’ does not match format ‘%m %d %H:%M:%S'”

What should you do?

Solution
Replace the “%m” with “%b”.

import datetime
log_reader = open(‘auth.log’, …

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How Do You Troubleshoot the Python Problem “TypeError: ‘module’ object is not callable”?

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Problem scenario
You run a Python program with datetime, but you get the error “TypeError: ‘module’ object is not callable.” What should you do?

Solution
Even though you may use “import datetime” at the top of the program, you should use “from datetime import datetime, timezone” at the top. If you used the syntax “datetime.datetime…”, you will need to remove one of the “datetime.” strings from the code.

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How Do You Write a Python Program to Extract Lines of a Specific Date?

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Problem scenario:
You have a log like this:

Sep 18 07:28:11 server1 sshd[29284]: Received disconnect from 125.52.17.109 port 46970:11: Bye Bye [preauth]
Sep 18 07:28:11 server1 sshd[29284]: Disconnected from 125.52.17.109 port 46970 [preauth]
Sep 18 07:28:11 server1 sshd[29282]: Failed password for root from 51.12.19.109 port 24844 ssh2
Sep 18 07:28:13 server1 sshd[29287]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=119.29.155.214 user=root
Sep 18 07:28:13 server1 sshd[29282]: Failed password for root from 51.12.19.109 port 24844 ssh2
Sep 18 07:28:14 server1 sshd[29282]: Received disconnect from 51.12.19.109 port 24844:11: [preauth]
Sep 18 07:28:14 server1 sshd[29282]: Disconnected from 51.12.19.109 port 24844 [preauth]
Sep 18 07:28:14 server1 sshd[29282]: PAM 2 more authentication failures; …

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How Do You Troubleshoot a “SyntaxError: invalid syntax” Error in Python?

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Problem scenario
You do not know why you are getting the error. The line has an “l” (a lowercase “L”) or a numeral one (“1”) in it.

You may have identified that the line of code is different in one file from another. You cannot tell what is different about your code or why you are getting this error. What should you do?

Solution
Enter vi or open Notepad++ to view the code.

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How Do You Troubleshoot The Message “no module named pandas”?

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Problem scenario
From a Python command prompt or when you run a Python program, you get the error message “no module named pandas”. You have used pip and pip3 to install pandas. What should you do?

Solution
Use “python3” instead of “python” to ensure you are using Python 3.

You may also want to see this posting.

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