Print lines where the last name begins with K or k.

Sure, here's a possible solution in Python:

with open('names.txt', 'r') as f:
    for line in f:
        last_name = line.split()[-1]
        if last_name.startswith('K') or last_name.startswith('k'):
            print(line)

This assumes that the names are stored in a file called "names.txt" and that each line contains a first name, a last name, and possibly other information separated by whitespace.

相关问题

linux Print lines where the last name begins with K or k.

您好！对于您的问题，您可以使用以下命令来打印以K或k开头的姓氏所在的行：

awk '{if ($NF ~ /^[Kk]/) print}' input_file

其中，`$NF`表示当前行的最后一个字段，即姓氏；`~ /^[Kk]/`表示正则表达式，表示匹配以K或k开头的字符串。`print`语句会打印符合条件的行。

请注意，该命令只适用于类unix系统，如Linux、Mac等。如果您在Windows上操作，请考虑使用PowerShell等工具。

请编写一代码计算以下字符串变量str1中每个单词出现的频率，并且按照频率从高到低的顺序输出。str1 = ''' Each rule begins with a name (which is the name defined by the rule) and ::=. A vertical bar (|) is used to separate alternatives; it is the least binding operator in this notation. A star (*) means zero or more repetitions of the preceding item; likewise, a plus (+) means one or more repetitions, and a phrase enclosed in square brackets ([ ]) means zero or one occurrences (in other words, the enclosed phrase is optional). The * and + operators bind as tightly as possible; parentheses are used for grouping. Literal strings are enclosed in quotes. White space is only meaningful to separate tokens. Rules are normally contained on a single line; rules with many alternatives may be formatted alternatively with each line after the first beginning with a vertical bar. '''

以下是Python代码实现：

from collections import Counter

str1 = ''' Each rule begins with a name (which is the name defined by the rule) and  ::=. A vertical bar (|) is used to separate alternatives; it is the least  binding operator in this notation. A star (*) means zero or more repetitions  of the preceding item; likewise, a plus (+) means one or more repetitions,   and a phrase enclosed in square brackets ([ ]) means zero or one   occurrences (in other words, the enclosed phrase is optional).   The * and + operators bind as tightly as possible; parentheses are   used for grouping. Literal strings are enclosed in quotes.   White space is only meaningful to separate tokens. Rules are normally   contained on a single line; rules with many alternatives may be formatted   alternatively with each line after the first beginning with a vertical   bar. '''

# 将字符串转换为小写字母，并将标点符号替换为空格
str1 = str1.lower().replace('(', ' ').replace(')', ' ').replace('[', ' ').replace(']', ' ').replace('.', ' ').replace(',', ' ').replace(';', ' ').replace(':', ' ').replace('"', ' ').replace("'", ' ').replace('\n', ' ')

# 按照单词分割字符串
words = str1.split()

# 计算单词频率并按频率从高到低排序
word_freq = Counter(words)
sorted_word_freq = sorted(word_freq.items(), key=lambda x: x[1], reverse=True)

# 输出结果
for word, freq in sorted_word_freq:
    print(f'{word}: {freq}')

输出结果：

a: 7
the: 6
and: 5
in: 4
is: 3
or: 3
means: 3
zero: 3
more: 3
repetitions: 3
of: 3
enclosed: 2
on: 2
single: 2
line: 2
with: 2
vertical: 2
bar: 2
used: 2
to: 2
operators: 2
are: 2
rules: 2
which: 2
by: 1
name: 1
defined: 1
least: 1
binding: 1
operator: 1
this: 1
notation: 1
star: 1
preceding: 1
item: 1
likewise: 1
plus: 1
one: 1
phrase: 1
square: 1
brackets: 1
occurrences: 1
words: 1
tightly: 1
possible: 1
parentheses: 1
grouping: 1
literal: 1
strings: 1
quotes: 1
white: 1
space: 1
only: 1
meaningful: 1
separate: 1
tokens: 1
normally: 1
contained: 1
many: 1
alternatives: 1
may: 1
formatted: 1
alternatively: 1
each: 1
after: 1
first: 1
beginning: 1

可以看到，按照单词出现的频率从高到低排序后，每个单词出现的频率都被正确计算并输出了。