CONTINUAL INTEGRATION

Problem scenario
You are taking a slice of a Python string. You know that syntax like var_x[-2:] signifies the penultimate character and the last character of a string (called var_x). But you are only seeing one character -- not two. You expect to see two (or a different number of characters than what you are seeing). Why is the snippet printing out fewer characters than you expect?

Possible Solution #1
There could be an invisible "\n" attached to the string (e.g., at the end of the line). If you are using "readlines" to read an input file, there could be a "new line" or "line break" being processed as a single character. You may be seeing an incorrect number of characters in your slice/portion. If you are reading a file, and processing it line by line, you may want to use the .strip() function. This can remove the "\n" character that is getting picked up and ruining otherwise sound logic for your string manipulation task.

Possible Solution #2
There is an "if" or "for" loop or some logic in your program that is causing a special case to not process the way you are thinking about it. Sometimes a condition is met where a portion of code is entered or skipped, but we humans forget about this scenario. Use some intermediate print statements; this may be tedious, but you may be able to pinpoint the problem.

Problem scenario
You want to install gRPC and configure it for Python. How do you do this?

Solution
Prerequisites
You have installed pipe and venv. If you need assistance installing pip, see this posting for Ubuntu/Debian or this posting for a Red Hat derivative (e.g., RHEL, Stream, CentOS, Fedora) or this posting for SUSE. If you need help installing venv, see this posting.

Procedures
Run these commands:

python3 -m venv to_test
cd to_test
source bin/activate

Run this:

pip3 install grpcio

Problem scenario
When a number of lines of text are read from a file, the Python program sees each line as such. When a number of lines of text are in the program itself, that is you use a multi-line variable assignment in a .py program, Python sees the characters individually and does not distinguish between the different lines. The len() function reflects these differences. You want the Python program to read the text in the program as if it were read from the "with open" and "readlines()" function line-by-line -- not character-by-character.

For example, your source text could be like this in a standalone .txt file:

foo bar 123 456
cat dog 999 888
horse cow 333 777

When you read the .txt file in the Python program, each line of text is treated as a separate item in a list. In a Python program, you could have an assignment like this:

data1 = """foo bar 123 456
cat dog 999 888
horse cow 333 777"""

But the three lines would be treated as a single string -- not a list. You want data1 to be three lines of text and the len(data1) function to return 3. You do not want to have separate .txt files for the .py program to open. You want everything in a self-contained .py file.

What do you need to do?

Solution
Use .splitlines() and list(). Here is an example:

list(data1.splitlines())