索引数组:1 到数组的长度

Question

很抱歉标题不好，请随时将其调整为更合适的内容。

如何使用zsh或bash脚本为数组编制索引，就像我对下面R中的列表所做的那样;

# Some lists with the same number of elements
list1 <- list(sample(letters,10))
list2 <- list(1:10)
for(i in 1:length(list1)) {
  a <- list1[[1]][i]
  b <- list2[[1]][i]
}
print(paste(a,b))  # Or some other function where a and b are used simultaneously
[1] "f 1"
[1] "e 2"
[1] "t 3"
[1] "s 4"
[1] "c 5"
[1] "o 6"
[1] "p 7"
[1] "y 8"
[1] "k 9"
[1] "d 10"

下面的代码显然只打印两个列表中的最后一个元素，因为我还没有找到一种方法来对数组的长度做 1

# dummy data
echo 'A 1' > A.txt
echo 'B 1' > B.txt
echo 'C 1' > C.txt
echo 'A,2' > A.csv
echo 'B,2' > B.csv
echo 'C,2' > C.csv
txtlist=(*.txt) # create an array of .txt files
csvlist=(*.csv) # create an array of .csv files
# in zsh $#array returns the length of the array, so 
for i in $#txtlist; do
    a=$txtlist[i]
    b=$csvlist[i]
    echo $a,$b  # Or some other function where a and b are used simultaneously
done
#C.txt,C.csv

任何指示将不胜感激，谢谢！

Answer 1

bash和zsh都知道C风格的for循环：

从man 1 zshmisc（man 1 bash基本相同）：

for (( [expr1] ; [expr2] ; [expr3] )) do list done
       The  arithmetic expression expr1 is evaluated first (see the section `Arithmetic Evaluation').  The arithmetic expression expr2 is repeatedly
       evaluated until it evaluates to zero and when non-zero, list is executed and the arithmetic expression expr3 evaluated.  If any expression is
       omitted, then it behaves as if it evaluated to 1.

zsh示例：

for (( i=1; i<=$#txtlist; i++ )); do
    echo "$txtlist[$i]" "$csvlist[$i]"
done

bash示例：

for (( i=0; i<=${#txtlist[@]}; i++ )); do
    echo "${txtlist[$i]}" "${csvlist[$i]}"
done

Answer 2

对不起，我不确定是否理解你的例子，但是，你可以在 bash 中做这样的循环：

myLength=${#myArray[@]}
for (( i=1; i<${myLength}; i++ ));
do
  echo ${myArray[$i]}
done

Answer 3

使用以下

语法：

$ x=(1 2 3 4 5)
$ print $x
1 2 3 4 5
$ print ${x:1}
2 3 4 5