Search the log

Write the codeMedium 2 stages

The mission log records thousands of lines a day, and the flight director only wants to see the errors. Before the log viewer can highlight them, it has to know whether a line contains ERROR, and where.

Search a log line, then pull out the error message that follows.

Print whether the line contains ERROR, and the index where it starts:

Contains ERROR: True
Starts at: 13

"ERROR" in line gives True or False. line.find("ERROR") gives the index of the first character of the match, or -1 if there's no match at all.

Search the line

Works for a line without an error

Finish stage 1 to unlock this stage.

The flight director wants just the message that comes after ERROR and the space after it. Add a line:

Contains ERROR: True
Starts at: 13
Message: Fuel valve 2 not responding

Start the slice from where ERROR starts, plus its length, plus one for the space, and leave the end out. The time in brackets can grow longer, [T+100:02:00], so work from position, not from a fixed number.

Print the message

Works when the time is longer

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Hints

Methods find, count, replace and split

methods-find-replace-split.py

# Searching, counting, and splitting strings

# A snippet of mission log text
report = "Mars rover Curiosity landed. Curiosity is still active."

# .find() returns the index of the first match, or -1 if not found
position = report.find("Curiosity")
print("Curiosity first appears at index:", position)

missing = report.find("Voyager")
print("Voyager index:", missing)  # -1 means not found

# .count() returns how many times a substring appears
mentions = report.count("Curiosity")
print("Curiosity mentioned:", mentions, "times")

# .replace() can clean up or swap text - here we redact a name
public_report = report.replace("Curiosity", "[REDACTED]")
print(public_report)

# .split() breaks a string into a list, using a separator
crew_data = "Mark Watney,Botanist,Ares III,Sol 18"
fields = crew_data.split(",")
print("Fields:", fields)

# We can grab individual pieces by index
print("Name:", fields[0])
print("Role:", fields[1])

# Splitting on whitespace - no argument needed
sentence = "Houston we have a problem"
words = sentence.split()
print("Words:", words)

Open the full example

script.py

PythonLn 1, Col 1Spaces: 4

Loading the Python environment…

Command-line arguments (sys.argv)

Separate arguments with commas. They're passed on every Run as sys.argv[1:].