Question

# simulate data
id=c(1:30)
house_type=sample(c("3STR","2STR","1STR","DETC,1STR","2STR,DETC","OTHERS"),20, replace=TRUE)
house=data.table(id,house_type)

# I want to create a house_type2 variable in house data.table
# In the real data, there are many other house type, with 1/2/3STR embeded in these house_typ. 
# I want to extract the STR (how many story) information from the data.

house[,story:="others"][str_detect("3STR",house_type),story:="3STR"][
  str_detect("2STR",house_type),story:="2STR"][
    str_detect("1STR",house_type),story:="1STR"]

模拟数据看起来确实是样本；在实际数据中，house_type字符串的变化更大。我设法用data.table链接语法做到这一点。但是我在问一种更优雅的方法：定义一个函数以提取故事并将该函数应用于house_type列。

Answer 1

您可以使用正则表达式提取数字：

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    <?php foreach ($comments as $comment): ?>
    <?php if ($comment->comment_approved != '0'): ?>
        <?php
        $attachments = get_posts(array(
            'post_type' => 'attachment',
            'numberposts' => -1,
            'post_status' => 'any',
            'post_parent' => $comment->comment_post_ID,
        ));

        if ($attachments) {
            foreach ($attachments as $attachment) {
                echo wp_get_attachment_url($attachment->ID);
            }
        }
        ?>
<?php endif;?>
<?php endforeach;?>

使用data.table和自定义函数从字符串变量中提取变量

1 个答案: