Write into tcl dictionary - dictionary

Question

I am relatively new to tcl dictionaries and don't see a good documentation on how to initialize an empty dictionary, loop over a log and save data into it. Finally I want to print a table that looks like this:
- Table:
HEAD1
Step 1 Start Time End Time
Step 2 Start Time End Time
**
- Log:
**
HEAD1
Step1
Start Time : 10am
.
.
.
End Time: 11am
Step2
Start Time : 11am
.
.
End time : 12pm
HEAD2
Step3
Start Time : 12pm
.
.
.
End Time: 1pm
Step4
Start Time : 1pm
.
.
End time : 2pm

Answer 1

You really don't have to initialise an empty dictionary in Tcl - you can simply start using it and it will get populated as you go along. As mentioned already, dict man page is the best way to start.
Additionally, I would suggest you check the regexp man page as you can use it nicely to parse your text file.
Not having anything better to do atm, I cobbled together a short sample code that should get you started. Use it as a starting tip, adjust it to your particular log layout and add some defensive measures to prevent errors from unexpected input.
# The following line is not strictly necessary as Tcl does not
# require you to first create an empty dictionary.
# You can simply start using 'dict set' commands below and the first
# one will create a dictionary for you.
# However, declaring something as a dict does add to code clarity.
set tableDict [dict create]
# Depending on your log sanity, you may want to declare some defaults
# so as to avoid errors in case the log file misses one of the expected
# lines (e.g. 'HEADx' is missing).
set headNumber {UNKNOWN}
set stepNumber {UNKNOWN}
set start {UNKNOWN}
set stop {UNKNOWN}
# Now read the file line by line and extract the interesting info.
# If the file indeed contains all of the required lines and exactly
# formatted as in your example, this should work.
# If there are discrepancies, adjust regex accordingly.
set log [open log.txt]
while {[gets $log line] != -1} {
if {[regexp {HEAD([0-9]+)} $line all value]} {
set headNumber $value
}
if {[regexp {Step([0-9]+)} $line all value]} {
set stepNumber $value
}
if {[regexp {Start Time : ([0-9]+(?:am|pm))} $line all value]} {
set start $value
}
# NOTE: I am assuming that your example was typed by hand and all
# inconsistencies stem from there. Otherwise, you have to adjust
# the regular expressions as 'End Time' is written with varying
# capitalization and with inconsistent white spaces around ':'
if {[regexp {End Time : ([0-9]+(?:am|pm))} $line all value]} {
set start $value
# NOTE: This short example relies heavily on the log file
# being formatted exactly as described. Therefore, as soon
# as we find 'End Time' line, we assume that we already have
# everything necessary for the next dictionary entry
dict set tableDict HEAD$headNumber Step$stepNumber StartTime $start
dict set tableDict HEAD$headNumber Step$stepNumber EndTime $stop
}
}
close $log
# You can now get your data from the dictionary and output your table
foreach head [dict keys $tableDict] {
puts $head
foreach step [dict keys [dict get $tableDict $head]] {
set start [dict get $tableDict $head $step StartTime]
set stop [dict get $tableDict $head $step EndTime]
puts "$step $start $stop"
}
}